i was debating on puttin on exaust but i know it adds little HP....the thing is i have a y pipe which helped a lot but do you guys think changing my exhaust would do anything? also, does that mean our stock exhaust system is good enough ?

 

I would suggest 'b pipe fix' from warpspeed and a aftermarket
muffler...
What, maybe 7 hp and better gas mileage.

 

Get a B pipe and a 5th gen muffler. Y pipe and an aftermarket muffler will be drony/noisy.

DW

 

thats what im gonna do when i get my y pipe

 

It's just that the stock exhaust was designed well for the car at the output the stock engine makes. So if all you guys want to do is intake and y, you aren't getting to an output where the exhaust becomes a weak link.

Talk to guys running 100hp+ over stock, and I'm sure they'll tell you the stock exhaust is restrictive. Those with intake and exhaust getting 25-35hp, won't gain much, maybe 5 or so.

 

yup the stock exhaust doesnt let the car breath with a ypipe etc..in order to have maximum gains there cannot be a weak link in ur exhaust setup.

 

Loren had 290 at the wheel, added a CatBack, and only gained 7hp.

I've never seen any proof that even when boosted, adding a CatBack helps.

If you see some, let me know, because I've asked before and noone had proof it helped anything more than 10hp.

IanS

 

Don't forget, there's a HUGE difference on the optimal exhaust depending on turbocharging or supercharging.

 

Although the dynojet 248C is a good tool, the load it puts on the engine is not the same or as much as the load of driving the car on the street.
The more time you let backpressure build up, the more HP that will be lost.

From most to least restrictive, I would guess it goes like this:
1. Y pipe
2. B pipe
3. Muffler
4. Catalytic converter.

Everything closer to the engine (even at the same diameters) is more restrictive. Because closer to the engine are hotter and hotter gasses which means lots of pressure. The exhaust gasses lose around a 1000F degrees from the exhaust valve to the muffler. Don't worry, your engine isn't melting down. Its just the temperature of the gasses; the metal isn't getting that hot.

 

Get a Y-pipe, B-pipe and high-flow cat(or testpipe)

Done!

 

I agree with you Brian. I just can't put a loud exhaust on an Infiniti, it just does not seem right to me.
I will probably just get the Y-pipe, B-pipe fix, and put on a better looking tip.

 

Ummm.

That's what I'm saying. I have never seen any proof that there is any major difference.

283hp - (Only Y-Pipe)
290hp - (full Catback added)

Doesn't sound like a HUGE improvement at all.

And noone else has any proof, so I'm inclined to believe that a CatBack on a boosted maxima still doesn't have much difference at all.

I would love to see a before and after Dyno of a CatBack being added to a SC besides the one I have seen. I would LOVE to be proven wrong, but I don't think I will be. I've asked several times, and noone has any substantial proof FI+CatBack helps much at all.

IanS

 

if one has CAI and y-pipe, a B-pipe and stock muffler should be good right? why not keep stock muffler?

 

Y pipe for the performance
Cat-back for the sound.