Are the flanges on the muffler the same sizes or will I have to swap out the entire stock exhaust?

 

you should manage to get a universal muffler to fit on the stock exhaust.......millions of people have done it before......usually universal mufflers are made to fit on 2.25 inch piping

 

I was planning on eventually replacing the entire exhaust will this be a problem or will the universal muffler fit the aftermarket exhaust piping too?

 

Why not start at the y-pipe and work your way back? The stock muffler is not that restrictive, plus it keeps things quiet even if you replace everything else. It all depends on what you are going for.... I have no experience with the universal muffler, sorry.

 

the stillen muffler will fit directly on to the stock piping. and im guessing from the fact that you want only a muffler that you want sound/looks and the stillen has that. i heard its mad loud. but you wont have to weld