Do they effect sound of the exhaust or loudness?

 

I would say not enough to bother looking for a specific tip....just go with what you like as far as size/type. Best looking is 3.5" up to 4", anything smaller/larger looks funny.

I haven't measured the rough diameter of the cutouts, but TO ME the best fit would be a tip of the same diameter with maybe 1/4" gap between the tip and bumper nice and centered and both equal distance front to back.

I just measured my cutouts...they appeared to be roughly 5"....but I would go no larger than 4" to fill the hole.

 

Don't Know if they affect the sound or not. Once I bought my Flows it came with 2 1/2 inch tips. I graduated to the 4 inch. Like I said I really don't know about the sound but IMO it looks better..

 

if you get a flat tip, like a camaro, the sound may change slightly, but the only time you'll see a real difference in tips is with turndowns, which give a lotta drone w/ highway driving. they're a good bit louder tho

 

i used a flowmaster catback from a 96-98 GT on my car (everything is the same except the hangers and tips). the tips are 2.5" slash cut non rolled tips. i bought some 3 1/2" rolled tips and before i welded them on, with the car on idle sliding the tips on i could tell a SLIGHT change in exhaust tone, but nothing to brag about it was just for the sound.