I'm with Shayne. Possibly because it's THE most sensible thing he's ever said. Unless you want to hot things up a bit with new headers and a bigger bore, all you want is a tube from front to back. Usually called an exhaust.
Question - What do I replace my stadnard worn out exhaust with? Answer, a new exhaust. Question - how do I improve my car's performance? Ahh - that's different.
Jon is right, how long will the will the car last v how long will the exhaust last v the cost of std over stainless.
So really Carl, it depends. Petrol engines get through exhausts more often than diesels because of the products of combustion going into solution in the engine's condensate. These form a mild acid. If you run the engine long enough to boil these off, it's fine. But short trips are the end of an exhaust system. Stainless gets around this. But payback is over quite a long period. If the std exhaust is nearly as much as stainless, well, no brainer.
In a normal world, I'd stick a pattern part on. But for sheer vrooom, I'd stick a nice stainless bad boy on there. The extra cash is nothing to do with the exhaust, it's about paying for a smile.
C
