JJ I had a full 50mm system on my bike , now have a full 54mm system, must admit i prefer the 54 but i have done a few things to the bike....! Saying that the 50mm system was also good, the SP made 105 RWHP on the dyno with that system, a pc3 and a couple of other bits. So i`d say, as others have, depends on how much you have done/going to do to the bike, both good. My system may also be for sale soon if you are interested. Cheers Gav |