I think you might well get 2mph. I put on EMI Thunders and modified my intake suppressor on my '99 454 Mag MPI and gained 1-1/2 mph for the exhaust and 1/2mph for the intake, then lost 1/2mph to a drive shower. Those cast iron Merc manifolds are boat anchors! I also installed an adjustable fuel pressure regulator but the fastest boat speed ended up being at the factory pressure setting!

up date, on buds 35. adding msd box, 1.8 raito roller rockers, dicthing the the stamped steel ones. this is whalt thier telling him k&n air 8 to 12 hp--roller rockers 25 to 40 hp--haedders 40hp--brainbox,40hp set 5500rpm, fuel pressure set 39lbs. 87oct to 91 oct fuel. going to take it swimming this weakend. will send up date.

WOW 113-132 HP gain I am sure that it is going to help but I would bet that the biggest increase is going to be seen in raising the rev limit. Keep us posted.