replacing a factory exhaust with an aftermarket like ANSA or TUBI makes the car sound good but how much more power do you really get. i have heard reports of 15 to 25hp. is this accurate or is is one of these things that look good on paper? When i was racing we dynoed motors for days making changes that people swore would make more power and actually went backwards. as any person who works with a dyno knows 15 or 25hp is a very hard thing to find.