AsthmaMax11

iTrader: (3)

A few months ago I put the stock muffler back on my car and I feel like my car is being restricted some.
So how important would you say an aftermarket muffler is when you already have a good amount of bolt-ons?

Tatanko

iTrader: (34)

If you're that worried about it, go with something like the A33 muffler. It's less restrictive than the A32 muffler, but is still stock-ish. Don't get me wrong though, it sounds good

maximazation

iTrader: (11)

That feel is probably a placebo, your used to the sound and usually louder sounds feel faster.

Jime

iTrader: (10)

The fastest run on my car was with the stock muffler. I have a Vibrant straught thru that I can change in about 10 mins that I put on at the track. One day I was lazy and didn't change it and ran my fastest time so I think its the noise that makes you think you are quicker.

JClaw

iTrader: (17)

That may be true for a 5th gen but I certainly would not have left my original 95 catback/muffler on my car. The cattman is considerably larger (2.5") and doesn't have a crumpled section halfway through. Plus that thing was just rusted.

JSutter

iTrader: (46)

the stockmuffler is maybe 1-2 hp less

JClaw

iTrader: (17)

Depends whether you got a 3.0 or 3.5...

Nealoc187

iTrader: (23)

My fastest runs were with catback, but I haven't analyzed my average runs from before and after catback. Maybe I'll do that some time. I still have alot of timeslips to put in my spreadsheet, like 100 of em lol.

krismax

iTrader: (15)

My greddy muffler i can look right thru it the stock isnt even close cant even see light.

above 7k i can def feel a huge difference it gets drowned with stock.

AsthmaMax11

iTrader: (3)

interesting to see so many veterans with different opinions. The guy at the Dyno was telling me that the muffler is one of the most restrictive parts of the exhaust system. This didn't make any sense to me considering I've heard it's only a few whp difference.

What do you guys think of the cheapo Ebay mufflers?

JClaw

iTrader: (17)

The most restrictive part of the exhaust system is replaced by headers. The rest is far less important, but IMO if you're going to do it, do it once and do it right. I bought my entire exhaust system (Headers, Cat, Catback) at the same time. No rusted pipes falling off.

4DRSpeed

iTrader: (22)

Muffler is a muffler, it makes sound.

aussie983

iTrader: (16)

??????

njmaxseltd

iTrader: (19)

Actually it muffles the sound your engines exhaust makes.

Tatanko

iTrader: (34)

Well on 4th gens, the y-pipe is more the restrictive part of the exhaust. It differs too much from car to car to make a broad generalization about all cars.

Larrio

iTrader: (10)

I don't think the muffler applies much for horsepower gains

However I do think that the b-pipe, which is the most restrictive part does. The area under the curve gained just changing to a 2.5 inch b-pipe can be seen on www.motorvate.ca

AsthmaMax11

iTrader: (3)

Well let me ask you this,
When I put my stock muffler back on they had to replace some of my old piping with the stock diameter piping. (I had 2.5") It was only about 2 feet or so but do you think that would affect my car's power?

Larrio

iTrader: (10)

It probably wouldn't contribute much

the 2.5 inch b-pipe on 5th gens replaces two severe crush bends that hinders power, however the overall length of the extra diameter in the piping also helps a lot by freeing up exhaust flow

JC93SE

It might. For instance: the loss in area to drop from a 2.5" pipe to- say- a 2.25" pipe is close to 20%. I don't know what size pipe they put in when you changed mufflers (or what the stock size actually is), but that gives you an idea. I don't know for sure that a Maxima needs/uses "all" of a 2.5" pipe (it might), but since that's the next realistic size after 2.25", that's what we use (do they make 2 3/8" pipe?)

Further, if your 2.5" pipe was mandrel bent (as a good cat-back would be) and they crush bent any bends in the new pipe, that's potentially an additional restriction on top of any the reduction in pipe size would cause- which was 3/4 of the reason you got a cat-back/b-pipe in the first place. A good exhaust shop should have been able to fabricate a transition from the 2.5" pipe to your muffler... so why they didn't, I'm not sure.

If you have a tube in your mouth to breathe through, and I take it away and put a narrower tube in place of it, you might notice it depending on how hard you need to breathe- doesn't matter if it's two feet or two inches long. If I then put a couple of bends in it, that would narrow the tube at those bends more than the narrower tube by itself. You've gone to a smaller pipe on your car (potentially added retriction), and then partially restricted the flow with the crush bends (definitely added restriction). You may have restricted your exhaust twice!

The smaller diameter pipe on the muffler "may" have caused an issue even if you left the 2.5" pipe in place (with a transition). The crush bends are what is probably killing you most, but the muffler/pipe size and the bends together could be significant. Hope you kept the pipe they cut out so you can put it back later. My guess is that the car feels fine under most conditions, but you feel it when you WOT and get above about 4000rpm +/-. Your upper RPMs are choked off some.

JC93SE

I should add that even if you didn't have a mandrel-bent cat-back/b-pipe, a custom crush-bent 2.5" pipe would still be bigger in the bends than the stock pipe or crush bent 2.25" pipe.

The first problem is your pipe. The second "may" be your muffler.

2 Da Max

iTrader: (2)

i just undo my cat bolts on the ypipe and run like that at the track...now thats power.. but noisy as hell