ah you bought Bens one then

most of what ive done for fitment etc is on my thread on the RSOC
http://bbs.rsownersclub.co.uk/showthread.php?t=224282
if you need more detailed / in depth info PM me on the RSOC forum as i frequent there a lot more than here, happy to help you get it fitted mate,

im almost finished mine just waiting on a few parts then it will be off for mapping, so i will beable to let you know the difference, but im expecting it to be much better through the higher RPMs as its quite a nice design for a manifold nice big plenum and long runners , but at lower rpm im unsure as to how it will affect running,

also you will need an oil cooler as the water / oil cooler system from the Rs wont fit with the new manifold, im expecting a new kit for the RS from HEL to arrive this week, so fingers crossed i can get it installed and let you know how it fits etc, as im not 100% happy with the setup i put in place at the moment,

anyway any more infor you need PM me on the RSOC mate, i will try and help where i can,