Mismatching inlet diameters
 

Hello,

Quick question: I have a Beluga Racing Y-pipe, and Beluga axle back (both 2.5” inner diameter), attached to the stock midpipe (2.25”). It sounds great, but I’m curious if there’s a significant enough performance difference that warrants purchasing a matching midpipe, or completely new exhaust system.

I’m not proud, but I can’t be the only one who has frakensteined an exhaust together.

I wouldnt see any issues with the setup unless you dont like the catback sound. If you are going to try to push power you could get some 2.5 test pipes. I have the opposite problem I have 2.5 test pipes and the previous owner/shop put a 2.25 cat back on it for some strange reason. I want to change it out but I'd like to maybe set up a buyer for the current catback obviously for $ concerns before I take it off and it sits in the back yard.

Definitely a bottle neck with the smaller in the middle.
No problem stepping up as you go back and might even help flow as the gasses expand.

I had a horrible drone with (anti reversion) test pipes, a megan Y, stock mid and medallion axle backs.
Was looking for a properly sized mid pipe when I decided **** it.
And went with long tubes plus a full cat back system.
So I can't tell you if the stock mid pipe was to blame or not.