alright mate i've done this to my GTi its well worth the effort, as for valve springs i wouldn't know??? i have changed the cams, MAF sensor (although they look identicle) and ECU, which is the main thing! without it it runs like a bag of s**t!!! its not as simple as unplugging one and plugging in the other though. there is a guide for it which is simple and easy to follow and most of all works! i've done it to my 1.8si and my GTi so defo works if you want it i'll dig it out and email it to ya, a word of advice though get a 4-2-1 exhaust manifold and the rest as it really does bring the engine to life, mine has done 120,000 miles and on the rollers the tech said it pulls all the way round the rev meter, hope this helps