JakeEbbon

It's a year 2000 and my boost gauge reads about 15 psi on full boost

Hey guys new to the forum and Scooby ownership thought somebody could point me in the right direction here....want to put an exhaust on my car my downpipe is rusted to all hell so I figured id swap it out for a stainless downpipe haven't fitted that yet it's 3 inch has a mini cat on it so not totally decat but I was thinking of going the whole hog and upgrading the rest of the exhaust to 3 inch all the way back....now the bloke I bought it off said my car has been remapped before because obviously after fitting the new exhaust I'll need a remap are the ECU's in turbo 2000s remappable if not I guess my cars already had another ecu put in? Is there a way to check this? And if my car does need a remap how much money would I be looking at?