I have been reading up pretty extensively on these intakes. Some of the Mach1/Cobra guys (NAZMAN and Angus in particular) have done a lot of work with these intakes and got them to flow well with runner work, runner shortening/reshaping, and custom lids. They also seem to be having some luck with rpm window switches activating the Intake runner tune valves (IMRCs in our ride) and running them as IMRCs. They are experiencing the 'Mid-rpm blues' as the transition between runners drops velocity and therefore torque/horsepower. They boys are also seeing the same with FR500 intakes. They have also seen more/less drop based on the cam profiles/timing used and the weights/trans/gears combos. Being our beasts are heavy autos (the very parameters the the AVI intake was designed to run for), it may be a viable intake for the MKVIII/C-head swap if we can get lids to fit under our hoods. That custom front-feed was being developed back in 05-08 but never made it to production as demand was just not there. With the FR500 intake and the advent of the Mach1/Marauder intakes and their ability for port work, the Aviator was basically left sucking wind.
Reason I am thinking of the Aviator intake is I have C-heads and finding a good 99-01/03-04 intake here for reasonable is next to none. I can get the complete Aviator intake for $50 and modify at my leisure. It, combined with long tubes, 96-98 Cobra cams with the ability to adjust timing via timing gears, and 4:10 trac-lock, the intake should work for good torque and horsepower.
