Inlet to plenum, a little clean up then its ready to weld adapter on, tpis also offers this service, if these mods work i will be offering them as a service thru my business along with ecm tuning but its not going to be cheap as this is very labor intensive. I will share exactly what i did for anyone who has the skills to do it themselves, Smitty

The procharger probably helps a little!

Heres a pic of new throttle body flange vs stock throttle body, before i attach the flange im going to make a adapter piece that allows me to bolt a stock throttle body on modified plenum so we can see difference on the dyno

Exactly what I learned. On a naturally aspirated engine your torque curve is greatly effected by runner length and diameter. The engine will pull better down low with some air restriction, but on top end it's all about max volume of air for power. To get the best of both worlds you tune the intake for a compromise on one end of that scale.

The other approach which OEM manufactures use is to mechanically vary the runner length, dia, or air volume somehow. Dual runners with butterfly valves on one set has proven successful. First introduced in 80's on the LT5 ZR1 Vette. Ferrari used a dual throttle body configuration with a mechanical plenum divider valve. At low RPM the valve is closed and each throttle body feeds one bank. At higher RPM the valve opens allowing both throttle bodies to feed every runner. Since the new LS engines are drive by wire, they now just control how fast the throttle body opens when you punch it. Thus lowering the torque curve by opening the blades slowly...

Yeah, drive by wire sux donkey balls. I put headers, exhaust and hp tuners on my 2010 ss auto. Dead launch at track with laptop recording:17% throttle (with pedal on floor), minus 8 degrees timing, i was shocked, no faster than before mods. Started turning tq mansgement down, got car from 13.70s to 12.70s, would still like to find a setting that speeds up throttle opening!!

Im guessing..............30-40 hp gain

If i cant get hp from modded intake within 10 to 15 of open plenum with a torque advantage my motors for my scarab are getting open plenum intake and regular throttle bodys. The wild card is shortening and porting lower intake runners which is virtually unheard of on 500EFIs, fwiw, Smitty

I did this on my 500/540 efi modified the throttle body also to single blade , no gains at all .

Arcticfriends will now also be testing a single plane intake with not only a 2200 CFM dominator throttle body but also with a swept 90* throttle body elbow that adapts the 4500 flange to a LS2 monoblade 102 mm throttle body.

If it works well on his dyno mule motor, I will be ditching my MPI intakes and bolting this setup on my bone stock 502 MPI and get some GPS numbers for direct in-boat comparison after proper tune. I know the intake might be a bit big for the stock long block but my full rebuilds/upgrades have been put off until next winter and I feel like some experimenting. Losing some low end torque will not hurt my planing ability. Should be interesting to see exactly how much the MPI intake holds the stock motor back even.

Did you have a bigger cam and better heads? Im doing this on a 540 that will definately be intake/throttle body restricted. I made a adapter flange last night that will allow me to make pulls with big throttle body vs stock