Ahh, well that's a debatable question. If you have all the stock restrictions and you put an aftermarket muffler on you probably won't notice much if anything real. If the stock muffler is the weak point of the system then you may. It all depends on the car, some have mufflers that are horrible and restrictive and a fairly well flowing rest of the system, if that is the case then you will see something. If you have a decent stock muffler and a crappy system before that then you won't see much. If you're planning on doing the exhaust then the muffler's a good place to start, it can give you a nice sound if that's what you're looking for and it's usually one of the easier pieces to put on. I was disagreeing with you staying it would not increase HP, not saying that you'll always see a noticable gain without a dyno showing you the differance.

 

Well, you guys have to remember, the 420a powered DSM's have a more restrictive exhaust sytem than the 4g63 powered cars. Knowing that, any change on the exhaust system will have a minor effect. At one point in the powerband, the exhaust system will eventually become the bottleneck for exhaust flow. While there is a resonator and a cat in place in the exhaust system, @ 7500rpm, the muffler becomes a more likely culprit for interrupting flow. Hey, if you see a 1hp gain at 7500rpm, it's still a gain, right?

 

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im with you 1hp 2hp. if its more then what i had then i all for it.

 

The straight through will flow the air like a resonator basically.

Noticeable HP is not 2-5hp. I would go with a nice 2.25 system if you can find it. Be ready for the Honda noise though, it is NON-turbo so the difference is noticable. Not saying turbo is better, just saying it is different. Different engines=different noises.