I have an '03 305/555 with straight pipe factory exhaust. (no muffler) I know I would gain by having an aftermarket system but is the price worth the gain? how much do I have to gain over stock?

 

If pretty much stock you won't see much of a gain if any at all.

I'm still running the stock exhaust with my mods.

MikeyB

 

I waited till my rotted out and the replaced the exhaust with a 304SS Hog 4' turbo back with the 04.5 elbow. The only difference is the loudness, although many here have said that your egt's will drop by 50-100 but since I don't have any gauges yet I don't really know.