If you check back this question went through a month ago or so. Offy and Mondello have tunnel rams. Heres my 2cents worth;
Tunnel rams are made for high rpm operation, 4500-7000 now there may be some jets operating in this range but damn few. this manifold lacks signal and velocity in the 3-5500 rpm range that most jet boats live. I run a torquer with a 850 double pumper. This seems to be a good compromise between mileage & Performance. My own opinion(no Dyno Results to back it up) is that 90% of the tunnel rams out there are for looks. aka a penis extender, mental masterbation ect.