ok you know how you would use a header reducer to go from a 3" collector diameter to a 2.5" diameter pipe, or what ever sizes. do they make opposite that. for example to go from 2.5" to 3", or what i just have to fab one up on my own.

 

I cant say Ive seen what your needing. You going to have to get a 3 to 2.5 reducer and attach it to the flange. That you can find at most parts stores.

 

you can probably buy those because i just got a set of dynomax headers shortys that come with reducers to fit onto the stock y pipe that you bolt flange to flange then weld or clamp to whats already there that it will slide into

 

flowmaster makes collector reducers without flanges, just weld on style. you could just turn them around the way you need them. not sure what sizes they have but i've seen them at summit.