Bought a 3" MRT single-tip axle back but don't know if it will have good results bolting up to my stock midpipe. looks like the flanges fit together but the pipe diameter is way bigger and might mess up the air flow. will that be an issue with the bigger pipe downstream?

 

you'll be fine as long as they match up and bolt together

 

it will be fine

just go to a muffler shop and have a mid pipe made its super cheap like 60$

 

yeah that might be a good idea

 

Idealy you don't want to have that sudden increase in size. You'd want it to taper so that you don't create drag. Going directly from 2.5" to 3" is so minor though that you most likely won't even notice any negative effects.