I've been looking around for an exhaust system for my IS350 and noticed a few claiming a 20+RWHP increase which is a pretty insane increas for a NA motor. This leads me to believe that the stock exhaust system is quite restrictive. I know a few of you here have aftermarket setups on your 350's and my quesion is about the sound. I would like to keep it as quite as possible, infact, the sound level from the stock exhaust would be ideal, but I know that may be asking for too much. I don't mind a slightly louder note as long as its a deeper sound and not the annoying hi pitched tone that you hear on those raced out honda's and what not.

I'm also concerned with vibration and sound resonating in the cabin, especially at lower RPM cruising speeds.

Is there a system available that will meet my needs? And to those that alrady have an aftermarket exhaust, how is it as far as sound, vibration, and resonating in the cabin?

 

In a word, no, you're not going to find a system like that.

In order to generate anywhere near 22whp from an exhaust on an NA car (a number I still don't recall having seen proved), you're going to have to remove some if not all of the catalytic converters on the car, and also replace the resonators/mufflers with less restrictive pieces.

That means more noise, plain and simple. It can be moderated, but at the expense of all that power. No free lunch, sorry.

 

Yeah, I figured as much. I don't really mind more noise per se as long as its the right type of noise and I can avoide sound resonating in the cabin. What I mean by that is when the frequency of the exhaust happens have the effect of making the cabin vibrate causing you to "feel" the exhaust note from all around you. Especially rear seat passangers.