Will running a 2.5" magnaflow to a megan 3" y pipe outlet cause rasp???

I looked up y-pipe on http://www.350z-tech.com/zwiki/Y_Pipes and i got this

........"It is important to match pipe diameter of various exhaust components. A 3" y-pipe section dumping into a 2.5" rear exhaust section may cause undesirable sound (raspiness) and loss of power. "

seems like i answered my own question, but in looking at exhausts available and y pipes available.......a lot exhausts are 2.5 piping, and most aftermarket y-pipes have the 3" outlet that bolts to the exhaust pipe.


Any thoughts???


here's a picture

 

fIirst off, I would think that any system that didn't have a mid-pipe resonator would be raspy.

Second, will the 2.5" Manaflow bolt up to the 3" Y pipe without mods?

 

It'll bolt up fine. It'll work fine, but not sure how great it would be to have a 3" to 2.5" piping. You can always have an exhaust shop weld in a reducer cone to smooth out the air flow.

 

do you think it would be easier to have the shop cut out the 3" section, and just weld on a 2.5" section?

I'm not quite sure how these things work, cause if you put on a cone, it would make one of the pipes longer, and then you'd have to cut the other pipe shorter???? like i said, i'm not quite sure how they work.

 

By the looks of the exhaust set-up, I would just have a few inches of the midpipe cut to make space for the reducer cone.

 

Think of you exhaust system as a flowing drain system. lets say you want the most flow that you can possibly get, so you would want to match your piping as close as possible. You would actually loose power and gain alot of rasp, because imagine running on concrete and then trying to run on sand, thats what your exhaust flow will be like. Most people on this forum use full systems that keeps the piping diameter consistent.

 

well in that case, what is the diameter of our oem y pipe??? is it 2.5 all the way through, to even the outlet hole?