this may be a stupid question but can an f4 exhaust fit a f2/f3 header?. Im talking like slip on to the header?

 

So you're talking about just an aftermarket slip-on can? If so, just measure the dia. of the can inlet & the header outlet (where the header & can attach). You may have to make a cone shaped connector that widens if the can is bigger.. I hope that's what you're talking about lol

 

2" opening on the pipe?

Yes.

1st gen R6 pipes will fit also.

 

thanks