I'm out of warranty so it's time to go for it.

Can I expect any performance improvement by changing my STi backbox for Scoobysport or any others for that matter? Most of the threads refer to UK cars which, I guess, come with a more restrictive system as standard. Would I be right in thinking that the Pro drive BB is in fact the STi item anyway? My STi BB is certainly quieter than the Scoobysport item, which would concurr with others comments.

Also, can anyone comment on improvements experienced with de-catting this type of car - either in isolation or in conjunction with other mods. I'm thinking Scoobysport centre section or similar.

 

Backboxes alone make little any difference. If someone tells you otherwise they are lying. Major improvements are had by rep[lacing centre resonance or cat with a straight trough pipe, and by changing the downpipe to one that allows wastegate exhausts to flow better and also removes the cat.

These will show you a significant difference.