I've had a second-hand prodrive downpipe cat fitted on my bugeye sti for a good few years now but recently discovered that it has rotten away where it meets the exhaust! So now I need a replacement as there is a leak.

I believe this is a 100Cel cat, so I would like to replace like for like really as I would assume I'd need a map again if this was to change.

Another consideration is the fact that my cat back exhaust is 2.5in rather than 3in. This is a decent Hayward and Scott Scoobysport system that I bought from new at the same time i had the prodrive cat fitted. (I'm very happy with it, as it makes a decent noise but not so much that it gets annoying and also meets track day noise limits)

I'm running approx 330bhp, no short term plans to increase this but would never say never (If I did it would be 400 max)

^ point to all this, if I go for a downpipe with 2.5in exit then I assume I would need to replace the downpipe yet again if I were to ever change to a 3in system? Which I guess should be done if I were to up the power one day

Options appear to be:
- new 2.5in exit downpipe. Keep 2.5in cat back. Stick with 2.5in even if I upped the power further.
- new 3in exit downpipe and 3in exhaust system. Sell my 2.5in H&S cat back to 'future proof'
- new 2.5in exit downpipe. Some kind of gasket/taper if i were to go for 3in cat back further down the line.

Bit clueless on this, anyone have any advice or recommend a suitable, decent downpipe replacement? (will probably go for brand new, as used prodrive ones seem to be a bit thin on the ground these days and most have probably seen better days)

Cheers

 

https://www.scoobynet.com/subaru-par...ports-cat.html