I know it's not ideal but I have a 2.5" centre section that I need to fit to my 3" downpipe. Will it fit ie are the flanges the same size?

 

When I put on my revolution 3 inch exhaust it fit straight in the 2.5 down pipe, not sure on others but I think you should be ok just to put on

 

Iv got my 2.5 magnex system mated up to a 3"cobra sports cat downpipe .had to use the 2.5 fire ring and stretch it over the 3" downpipe but it blows a little when cold so im on the look out for a quite 3" cat back as its not ideal long term bud

 

i bought an adapter 3" to 2.5" from flat four online a couple of years ago for £25 delivered if that helps

scoobyparts.com also have some.