Looking at a stainless set on ebay.

These are 1.8" primaries, but the collector outlet is only 2.75.

How much with the 2.75" collector affect performance compared to a 3" outlet?

http://cgi.ebay.com/ebaymotors/1993-...Q5fAccessories

That price is so good I'm really tempted to jump on it, as I'm not all too enthused about picking up another steel set with coating, esp. seeing how quick the Y pipe's rust away.

 

Its only 1/4" and since your exhaust prol takes two 3" and puts them into a single 3" I doubt you would ever notice a difference between 2.75" and 3".

For that matter when guys use typical clamps on their exhaust its crimped down that same 1/4" so whats the difference?

 

Also, the Y pipe that comes with the system is 2.75" tubing as well as far as I can see.

Most setup's are 3" collector and Y pipe. I don't know what kind of difference this will make, but I know my Mac setup is 3" collectors, to 2.5" y pipe, with a 3" collector outlet to a 3" exhaust.