So I currently have the stillen catback exhaust system on my car for about 6-7 months now. No Intakes or HFC. Its been a while since I drove a stock G35 and I have forgotten how that drives.. until today. I had my car serviced at the stealership today and had a loaner given to me. Its an 08 g35x. I have the 07 g35x.

I noticed that the loaner had more mid range punch compared to mine. More usable power around the 2000-4000rpm range. Much quieter than my ride.. thats for sure ( I have to admit, I kinda liked it :S ...) The engine thrust felt more solid it would seem.

So after I got my car back, I tested it immediately like the way I was driving the loaner. I felt my car lacked the mid range punch. Instead, it wanted to revv high to match the thrust of the loaner. In other words, my car with the aftermarket exhaust has become a high revving screamer rather than having usable power in the lower rpm ranges.

What gives? Is it because of the lack of backflow that I have lost since I have the aftermarket exhaust? Could it be that the stock exhaust system is still much better suited and provides better performance than an aftermarket one? (which makes since being that our ECU was tuned with the stock not the aftermarket).

If there is any positive to any of this, (aside from looks and sound the aftermarket exhaust gives you), I do feel the car climbs the rpm quicker than stock. But I have inadvertedly lost lower rpm thrust... which sucks in my opinion.

Any thoughts guys? Have you guys experienced the same with your aftermarket exhaust?

Wes

 

Well, while i was reading about exhausts because i wanted to change my Y pipe to a H or X pipe, seems like the Y pipe is more restrictive but it gives a better low end torque. Isn't Stillen a catback? maybe you no longer have a Y pipe.

 

I definitely didn't lose anything with the FI system. In fact, the car is much peppier and seems to be a bit quicker to respond.

It's hard to compare one car with another. The ECU has a lot to do with it. That loaner was probably driven a bit hard by the last few people who had it.

 

I hope its just the manner in which my car has learned to drive as a result of my driving input as of late (since its winter) not cuz of the exhaust.


hmmmmmm....

 

drive your car in maniac mode for a few days and it will learn that you mean business

 

When I first got my FI exhaust on, I thought I made a mistake b/c it was too loud and definitely felt soft off the line and at lower revs. Then, somewhere around 100 miles later, I floored it in this one stretch and the car took off with traction control barely able to keep the tires from peeling out. It felt like it took about 100 miles or so for the ECU to adapt to the exhaust. IMO, the exhaust has gotten quieter as well (either that, or I've gotten used to it).

Now, I do notice that the car's initial acceleration still feels softer than stock at partial throttle. At full throttle, it definitely feels faster b/c traction control kicks in more now over the same stretch of road.

 

So you do experience what I mentioned at the lower rpm ranges...

but I do agree with you, the car is a screamer at full throttle no doubt.

 

Hmm, you see cars from the factory are tuned for ppl that drive it and don't really care about performance(unlike us) therefore the companies tune the cars so that suspension is softer, there is more low end torque and quieter cabins to please them all at the same time sacrificing performance. So i'm guessing to increase performance you lose some creature comforts. In your case you have have a high reving, more torque and hp up top but now you have to work for it!

 

I hear ya... :P hehe

what would be most ideal is quiet when you want it to be, have low rpm grunt and still revv high and fast =) haha

 

Yes. But only at partial throttle. At full throttle, even at lower RPMs, the car RIPS and feels definitely faster than stock. This matches the dynos posted by terry which show the FI exhaust makes more power than stock at virtually all RPMs.

 

^ just stay in 2nd gear then

 

Some cars actually have this. I believe Corvettes, various Ferraris and even older cars like the Mitsubishi 3000GT had bypass valves that restricted the exhaust flow at lower RPMs for quieter noise and more torque. THen, the exhaust would open up fully at high RPMs for good top end breathing.

I don't think Corvettes like the Z06 and ZR1 could pass noise regulations w/o this.

 

The scion TC has this and so does the R32 and 335i, at 3k rpm a valve opens for a much better flowing exhaust. I read somewhere that the TC when the valve fully opens adds 5hp, no idea if it's right or not. With the 3000gt, it's quite in comfort mode, and sounds super mean when you turn the exhaust on sports mode. Wish my car had that. Aftermarket exhaust or stock exhaust whichever i feel like by pressing a button.

 

has anyone designed something like this for G35 & G37s?

 

they do have a vacuum operated flap valve in the exhaust piping that help close and baffle the sound. doesn't do much for power though, the torque on the 335 is due to the inline nature and tight turbo. most people that have these cars eliminate the flap valve.