I'm on a .48/60 Rog, the .48 is what will become the restriction at high RPM, a .55 or .63 would see me bigger numbers but my IB5 is going to be struggling around 300bhp anyway so I'm not worried lol
I've not actually had a chance to see what I can squeeze out of it though cos of all this rain, no traction means no mapping... also rain hitting the det can tubing sounds a lot like det too! lol