Yes - I've have that on my 964RS since about 1998. I'm very happy with it. Standard RS's are 260bhp - mine has 290. (also a cat change at the same time)
Have had the conversion done on both my RS's. It makes a significant difference to the pick up and throttle responsiveness Would defiantly recommend the upgrade.
Oooh yes -but include revised chip, revised cams, bigger throttle body, revised inlet, then we're talking +50bhp..... and £££££'s -glad somebody else did my Cup before I bought it!!