Quote Originally Posted by tony
That is what I'm wondering.. if its even worth it. 450whp safe or take the chance of going higher... I'll probably go the safe route for now. I currently have a 3in exhaust.. the next best thing is a 2.5in true dual exhaust but those are $1400 shipped, I cant justify paying that much for a couple of extra horses.
People that pay 1400 bucks for some exhaust are crazy as hell, the 2.5 inch they sell doesnt flow any better then the 2.5 inch custom mandril bent and installed exhaust you can get from a local shop for 400-600 bucks. 3 inch is normally plenty good, do like vteckidd said and dyno it with open DP if it makes that much of a difference then you need bigger exhaust, if not don't worry about it. there is always the option of running electronically controlled actuator that will basically dump the exhaust when you want that extra power and let you ride somewhat quiet when you don't.

To awnser you inital question , what causes the most stress on your motor belive it or not it is cold starts followed by detonation. I dont know what you are building your car for but if you want to get to a certain mark just to say you did (say 500 whp) and you are already at 450, then it isnt hard to to. just add some water injection or another power adder. Is it worth it when the rods are the weakest link? imo.. no. some people feel differently, but for me it isn't worth making an extra couple whp to take a motor that may last for 60k miles in its current tune state and blow it up just to say you are in the 500 whp club.. for a week. On turbo cars remember when you are even semi close to pushing the limits that keeping fresh plugs in the motor is a MUST.

Also remember when having it tuned there is reliable and then there is aggressive, know the tuner you are using and what style tuner they are.