aftermarket y-pipe with PRECATs, but higher-flow
aftermarket y-pipe with PRECATs, but higher-flow
Just messing around with some random ideas, so here's one:
DISCLAIMER: I don't know if this is a viable idea or not, I'm just throwing it out there for comments from people who KNOW what they're talking about...so don't bother flaming please. It may be a good idea, and it may not. I have no idea, which is why I'm asking.
Some people haven't gotten an aftermarket y-pipe for a few reasons
- noise
- they actually care about emissions (I don't, btw)
- they have to pass emissions inspections (including visual)...
so just thinking out loud here:
The problems with the OEM y-pipe that restrict horsepower are several:
1. the pipe shape is not condusive to free flow of exhaust
2. the precats restrict flow somewhat
3. not mandrel-bent.
now, most aftermarket y-pipes eliminate all 3 of these problems....but what if they only eliminated #1 and #3, but kept some kind of high-flow precats to keep them "street legal"
Sure, we can gain some power by removing our main cats and putting in a test pipe, but very few people actually do this. By the same logic, it is not the precats that are the big restriction, it is the SHAPE of the OEM y-pipe.
Like I said, just thinking out loud - but it would be interesting if cattman or warpspeed of some other exhaust company (frankencar?) could do a little experimentation with one of their y-pipes fitted with high-flow precats...
so, just thinking out loud here. Please don't be lame and say "you should just get headers" or "you can still pass emissions without precats." I know all of this, and am simply thinking of a y-pipe which would actually BE LEGAL in 50 states (which would sell well to people who want to "stay legal")...even if it produces 1 or 2 hp less than a y-pipe without precats.
most interested in responses from cattman, Blackbird, dmb, and a few others who actually know what they're talking about when it comes to exhaust!!
DISCLAIMER: I don't know if this is a viable idea or not, I'm just throwing it out there for comments from people who KNOW what they're talking about...so don't bother flaming please. It may be a good idea, and it may not. I have no idea, which is why I'm asking.
Some people haven't gotten an aftermarket y-pipe for a few reasons
- noise
- they actually care about emissions (I don't, btw)
- they have to pass emissions inspections (including visual)...
so just thinking out loud here:
The problems with the OEM y-pipe that restrict horsepower are several:
1. the pipe shape is not condusive to free flow of exhaust
2. the precats restrict flow somewhat
3. not mandrel-bent.
now, most aftermarket y-pipes eliminate all 3 of these problems....but what if they only eliminated #1 and #3, but kept some kind of high-flow precats to keep them "street legal"
Sure, we can gain some power by removing our main cats and putting in a test pipe, but very few people actually do this. By the same logic, it is not the precats that are the big restriction, it is the SHAPE of the OEM y-pipe.
Like I said, just thinking out loud - but it would be interesting if cattman or warpspeed of some other exhaust company (frankencar?) could do a little experimentation with one of their y-pipes fitted with high-flow precats...
so, just thinking out loud here. Please don't be lame and say "you should just get headers" or "you can still pass emissions without precats." I know all of this, and am simply thinking of a y-pipe which would actually BE LEGAL in 50 states (which would sell well to people who want to "stay legal")...even if it produces 1 or 2 hp less than a y-pipe without precats.
most interested in responses from cattman, Blackbird, dmb, and a few others who actually know what they're talking about when it comes to exhaust!!
Senior Member
Joined: May 2004
Posts: 6,187
Well I don't profess to know anything about anything, but I read on this website in the past 30 days that removal of the pre-cats is not illegal. Although they reduce emissions upon startup, the response in the thread stated something to the effect that their primary purpose is to also reduce noise levels upon startup. Consequently, I question whether it is illegal to remove them in all or any of the 50 states.
I have a stainless steel Budget y-pipe and don't give a rats a$$ about having removed the two pre-cats. I let my car idle for awhile and drive away slowly so I question what emissions I am spewing into the environment. I have yet to run through emissions testing, however.
I have a stainless steel Budget y-pipe and don't give a rats a$$ about having removed the two pre-cats. I let my car idle for awhile and drive away slowly so I question what emissions I am spewing into the environment. I have yet to run through emissions testing, however.
Senior Member
Joined: Nov 2000
Posts: 1,985
It is illegal to remove any emmisions component. This is different from the fact that cars do not have to have precats, its part of our NLEV rating.
Do people actually fail for not having precats? I know the cat but you have to have a smart tech to pick up the precats.
On a cali spec max I'm sure its possible but I don't think there would be a demand for it....its something NISMO would come up with.
Do people actually fail for not having precats? I know the cat but you have to have a smart tech to pick up the precats.
On a cali spec max I'm sure its possible but I don't think there would be a demand for it....its something NISMO would come up with.
Senior Member
Joined: May 2004
Posts: 6,187
Not all cars have pre-cats. Where I'm from, emissions testing is uniformly run at testing centers and all they test is emissions and the gas cap. A guy walks by holding a mirror on a handle checking for the existence of a catalytic convertor, but he certainly isn't looking for pre-cats and wouldn't have a clue if they were removed.
Donating Maxima.org Member
Joined: Mar 2005
Posts: 342
A Y-pipe is an easy install and many members have claimed huge gains from them on your car and have claimed to have passed emmisions. I say go for it and if it becomes a problem you can always re-install your stock Y-pipe.
i'm a little confused.
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
Senior Member
Joined: May 2004
Posts: 6,187
I think what they're checking for is that there is a catalytic convertor and not a straight pipe in its place.
With my Budget y-pipe, there is no difference from OEM at idle or cruising when the car is warmed up. However, with the removal of the two pre-cats the exhaust note at the back end of the car sounds louder if you are standing outside the car and listen after the car is initially started up. I think this is what the two pre-cats suppress.
With my Budget y-pipe, there is no difference from OEM at idle or cruising when the car is warmed up. However, with the removal of the two pre-cats the exhaust note at the back end of the car sounds louder if you are standing outside the car and listen after the car is initially started up. I think this is what the two pre-cats suppress.
Originally Posted by PoLo
i'm a little confused.
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
i also passed emissions with headers (no precats on my cali spec) with only my main cat intact. we have visual inspections here and they did not pick up on a thing. maybe they are more strict in other parts of the country though. he even asked why i had wrap around my exhaust and i just told him i bought it like that.
Originally Posted by PoLo
i'm a little confused.
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
1) what noise. i see literally no difference in tone with my Y
2) i passed emissions inspections
3) must be new to me. i never heard of visually inspecting a Y. if you passed emissions, then i'd think that's enough...it'd be funny to say "you're passing emissions. you are not making the world a more polluted place to live in BUT....we just don't like how it looks.....FAIL"
2) sure, we can all pass without the precats. Here in Va. we have emissions inspections annually (or bi-annually) and twice (on the maxima and previous car) the tech looked up under to see if he could see the precats. Again, getting around it isn't a problem though in most cases. But the one time you get caught, if the tech is an a-hole, you could get slapped with a $10K fine (or something to that crazy degree) for removing emissions equip....
3)uh...see 2
I'm aware that you can pass emissions fine without precats and that you are not melting the ice caps by not having them. I really have no problem with emissions considering even with no cats at all the maxima is cleaner than my Triumph
Like I said, just throwing out ideas...since the precats themselves don't restrict flow in a big way - it is the shape of the OEM pipe that does - just wondering out loud about a more free-flowing y-pipe that DID include precats of some sort. Who knows if it is possible or would have good results. I sure don't.....but if it could be done (and it would be completely legal, for anyone who cares)....why not try
all that said, I'm sure I'll put on a non-precat y-pipe in the near future.....
theres just been a shortage of interesting discussion in this forum recently so wanted to start some
Originally Posted by sloppymax
i think this would be geared toward the 3.0 guys. the y pipes for the 3.5 do not remove any precats which is why headers make much more power than them. since all precats in are in place, this is the reason why the tone of the exhaust changed very little if at all. the cali spec y pipe (3.0) removes 1 of the 2 precats and i believe the fed spec y pipe (3.0) removes both. this is one of the reason many 4th gen (mostly fed spec) 3.0 show greater gains on the dyno with just a y pipe compared to a 5th gen 3.0 with the same tranny.
i also passed emissions with headers (no precats on my cali spec) with only my main cat intact. we have visual inspections here and they did not pick up on a thing. maybe they are more strict in other parts of the country though. he even asked why i had wrap around my exhaust and i just told him i bought it like that.
i also passed emissions with headers (no precats on my cali spec) with only my main cat intact. we have visual inspections here and they did not pick up on a thing. maybe they are more strict in other parts of the country though. he even asked why i had wrap around my exhaust and i just told him i bought it like that.
I think the guy did the visual inspect up and under the engine (he wasn't looking at the main cat) either because the lower tie bar caught his interest or my intake did (He had the hood open)....either way, he busted me for my smoked side markers and made me change them out before I passed so who knows how much more **** the guy was gonna be
a few quick reactions...
Although removing the stock y-pipe on a 95-01 Maxima means removing one or both pre-cats, and this is clearly in violation of the Federal emissions requirements, it is almost unheard of for a Maxima to fail emissions with a performance y-pipe or headers AND a properly working main cat. So, while not legally in compliance, the car is operating under the maximum emissions limits.
[Keep in mind none of this has any bearing on the 02/03 y-pipes since they do not require the removal of any pre-cats.]
What you're suggesting can be done, though you'd lose a little hp and the price of the part would go up $150-200. The ironic part would be that even though you had a part that emulated the emissions function of the stock part, it would not be any more legal than the performance version without going through an exhaustive and expensive approval and certification process. Might make sense if you were going to sell 10,000s of Mustang parts, but it would never pencil out on a part for Maximas.
So, bottom line:
+'s - significantly cleaner emissions during the first few moments after start-up; slightly improved emissions at normal operating temps; possibly a nice warm fuzzy feeling inside knowing that although you were still illegal, you are "morally in compliance".
-'s - lose about 1-3 hp, depending on whether the stock y-pipe has one or two pre-cats in it (pre-cats don't rob that much power); pay $150-200 more for the part; subject to the same legal sanctions as the performance part w/o the pre-cats
I'd also add that on this basis, I would not see enough commercial potential to develop this part. Conversely, I'll mention that we feel very strongly about leaving the primary cat in place. Because the main cat is part of the y-pipe on 04+ Maximas (so it comes off when you remove the stock y-pipe), we will not release a Cattman y-pipe or header system for the 04+ Maxima without an integral main cat. We now have a high-flow metal cat that will work for that, so we're finally moving ahead with developing those gen6 exhaust parts.
Brian C Catts
Cattman Performance
Although removing the stock y-pipe on a 95-01 Maxima means removing one or both pre-cats, and this is clearly in violation of the Federal emissions requirements, it is almost unheard of for a Maxima to fail emissions with a performance y-pipe or headers AND a properly working main cat. So, while not legally in compliance, the car is operating under the maximum emissions limits.
[Keep in mind none of this has any bearing on the 02/03 y-pipes since they do not require the removal of any pre-cats.]
What you're suggesting can be done, though you'd lose a little hp and the price of the part would go up $150-200. The ironic part would be that even though you had a part that emulated the emissions function of the stock part, it would not be any more legal than the performance version without going through an exhaustive and expensive approval and certification process. Might make sense if you were going to sell 10,000s of Mustang parts, but it would never pencil out on a part for Maximas.
So, bottom line:
+'s - significantly cleaner emissions during the first few moments after start-up; slightly improved emissions at normal operating temps; possibly a nice warm fuzzy feeling inside knowing that although you were still illegal, you are "morally in compliance".
-'s - lose about 1-3 hp, depending on whether the stock y-pipe has one or two pre-cats in it (pre-cats don't rob that much power); pay $150-200 more for the part; subject to the same legal sanctions as the performance part w/o the pre-cats
I'd also add that on this basis, I would not see enough commercial potential to develop this part. Conversely, I'll mention that we feel very strongly about leaving the primary cat in place. Because the main cat is part of the y-pipe on 04+ Maximas (so it comes off when you remove the stock y-pipe), we will not release a Cattman y-pipe or header system for the 04+ Maxima without an integral main cat. We now have a high-flow metal cat that will work for that, so we're finally moving ahead with developing those gen6 exhaust parts.
Brian C Catts
Cattman Performance
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