welcome along buddy, plenty here to read up on.
The decat pipe on a GT3 is bent i believe, well it is on a mates of mine as i have just taken it off.
if you want to up the boost i suggest you get hold of a dawes device, but please please make sure you increase the fueling to accomodate the higher boost level. the vast majority on here Use a SEB chip to achieve this. £100 in general.