I just got a Random Technology downpipe and midpipe. I need to install this but I am not sure about the 3inch to 2.5 inch connection. I would like to replace the rear exhaust section with a straight 3 inch section. Then connect the downpipe-midpipe-rear section to my existing Prodrive axelback. I would have 3 inch all the way to the axelback.

Do I need a special adapter to connect these two different sized pipes?

Where is the donut gasket at? Midpipe to Rear Section or the Rear Section to Axelback? Or somewhere else?

Sorry I have not taken the exhaust apart so I dont have a clear idea as to what it looks like or how it is put together.

I still need to get the rear exhaust pipe section, so I dont know if I should get 2.5 inch or a 3 inch piece. And do I need a new donut gasket?

any input or experince would be cool, thanks