So true!!! Anything over 250WHP S/C, Turbo, or N/A requires engine management (piggy-back/stand-alone) and a good tune. Full set of gauges would be needed just to be safe. Better to know than, than to find out the hard way.
For bolt-on performance, you can start by perusing this sticky. Alot was discussed here. You can post your questions back here in your thread.
http://www.club-tc.com/forums/perfor...s-more-hp.html
434WHP is awesome. Try 739WHP as first reported exclusively by Club-tC
http://www.club-tc.com/forums/autocr...-tc-t-car.html This car was the original turbo tC from 2004 SEMA making 533WHP in street trim.
For the quick low down
click here for the Nitto Tire tC special.
BTW... I merged your 2 similar threads to keep the number of relevant threads. I did leave your original post as a redirect for 10 days so that you can specific posts.