FCHeman

ive been reading stuff about the 3 cat backs. which one is better for an NA? i read somethin (on a nissan forum) about the GT spec being too big for an NA, and it might lose torque and have no back pressure... dont exactly understand the back pressure part... so plz gimme some advices or like experiences that u've had with the exhausts

thnx

ViperDude152

You will get mixed answers with your questions. Reason is because some say if you have to large of pipe, then you will loose some low end but gain it in the high end.

Going with 2.75+ is just to big. Your exhaust ports on the motor are only....1.75"? I forget NZ Convert can you help with that one?

2.50" is all you really need and I think if I did the math right back then and if I still remember, 2.50 single is still just fine with room to play.

Its your choice, the GT I think would be better sound wise cause I think that has resonators. Although I think its 3". The N1 I don't think has resonators to help muffle the sound but you can get them in 2.5"

I made my self a 2.50 single from the manifold back. Exiting on the drivers side. I have a muffler that restricts the flow but I also will have a cutout on the muff so that wont be an issue.

Decision is up to you. I have heard good and bad about Apexi N1. Nothing about GT

Jager

iTrader: (10)

They all have resonators.

They all are loud, the GT Spec happens to be the deepest. Go with whichever one you want.

And most of your tuning is done by the time it reaches the cat-back, that's why its usually a preference of what you want.

Sideways7

iTrader: (7)

Any catback of decent size will yeild similar results, so its basically up to you on what sound you want. As stated, they will all be pretty damn loud. I have a single N1 and love it, but it gets annoying on long trips.

rolandofeld

not to threadjack, though along the same lines....

am i to understand there are (next to) no gains or losses between single and dual exhaust.(cat->back)?

if thats the case....i just like dual. (symetry among other things.)

Jager

iTrader: (10)

A dual exhaust has more surface area so it would flow more in theory.

rolandofeld

more flow =???????? less backpressure =???????? i'm dealing with n/a for clarification.

Anex 570

EXHAUST SYSTEM:

Our exhaust system was developed with many hours spent on our Dyno. We used an expansion chamber concept. We have consistently seen a 6 to 10 HP gain over other exhaust systems.

From: http://www.iscracing.net/2nd_Gen_Parts.htm

I run their system on my gsl-se which has a N/A s4 engine. This works on eaither. I should mention that if you dont have a header manifold, then its not worth the time.

Understand that the above statement from ISC is talking about header to resonator, to 3" pipe to "3 in and out muffler.

FCHeman

Im still trying to learn everythin about exhaust so what does more flow really mean? like the air going out faster... than what does backpressure mean? like theres too much space for the air to get out so it goes back in? .... please correct me if im wrong.... lol actually just correct me cuz i know that i got somethin wrong... and im still tryin to decide which one to get out of the three... i heard the GT sounds nice but its too big for an NA and N1 is hella loud and really nothing bout the N1 dual...

FCHeman

???

ViperDude152

Backpressure is basically resistance in the exhaust system, not allowing the exhaust gases to flow easily through the system and out the rear.

You want the least amount of backpressure / resistance as possible when designing or shopping for an exhaust system for your car.

Also depends on what you intensions are for the engine. Race Only? Street Legal with power?

You can do a True Dual exhaust which is when each exhaust port has its own 2" OD tubing. Some have found you don't get as much power with this setup as you would get when you have a collected system such as running 2 seporate 2" OD tubes near the diff and collect them into 2.25-2.50" ID Tube which goes into a muff out the back.

As for having more power with dual (y-pipe) exhaust vs single. Depending on how the y-pipe is bult at the merged point and what the diamter of the piping is, I would say you would get the same if not more or less rwhp.

This was said for Non Turbo motors. Turbo motors I believe get a bigger effect when going from exhaust systems with backpressure such as the stock system, to a high flow exhaust system. I have heard a few times the boost may increase. So watch out for that.

Be carefull when shopping for the n1 dual. I have seen many times when searching for n1 dual that you will usually find 2 muffs on the passenger side of the car at the rear instead of one on each side.

jonesfromindia

i own and use the N1. mine is very very quiet without the baffle in. i dont have a baffle. it comes with a resonator. but its not loud at all. i guess mine is different, becuase a lot of other people have said theirs is loud. i dont get it. but i do love the sound, it seriously sounds like a very very quiet very less powerful get engine when you rev it high.

speed_monkey

turbo or n/a?
turbo quiets the exhaust alot

ViperDude152

Do you still have the CATs too? Those can muffle a lot of the sound.

Jager

iTrader: (10)

Plus its subjective. It IS loud, as your local authority.