Try
www.vwvortex.com that become a member go to the 24 valve part and get advice.
I now neuspeed,GHL, GIAC(it's a computer chip) and Schrick are selling aftermarket parts for it. The problem is the 24valve VR6 was only sold for 2 years so not a lot of aftermarket parts have been made for it. I know
www.eiptuning.com can help ask for Rich and if you become a vwvortex member you will get a %10 discount. I know vfwengineering sells super chargers for them I think C2 motorsports also sells stuff for them. Try UnorthodoxyRacing they might have some stuff like pullies and a lightened flywheel for the 24v VR6. Not too sure on other companies.