My combo is a 6.0L LQ4 with LS3 cnc'd heads, edelbrock performer rpm, 219/228 hot cam and 4L80e trans in a 68 Convertible Camaro
Here's what Patrick from ProSystems emailed me :
For your program one of our big throttle blade, smaller venturi combo's is the best plan.
The design uses the 950HP style main body as a base and is a program that we have continually developed and uses the smaller venturi (750 size) for good low speed signal BUT the larger throttle blade for better high rpm power. LS3 heads love those big throttle blades.
It gives us the best of both worlds. Lots of low speed signal to give us a good high rate of engine acceleration so it comes out hard and responds to throttle movement quickly and by using the big 1-3/4" throttle blade (and our Billet baseplate), it allows more air in at light cruise so it drives cleaner AND it gives more high rpm power as well.
As you can be expect from a custom carburetor, it has our adjustable air bleed configuration, non-stick gaskets, Drag float, jet extensions, Billet baseplate, VENOM II Black billet metering blocks, anti siphon mods for clean braking, a complete wet-flow portfolio (for easy jet selection, but we're usually dead on or within 2 jet sizes), a real sharp piece with stepped dog leg boosters, big sight glass bowls and hi-flow needle and seats.
Typically I see a 15-30 hp improvement over an off the shelf unit with much better consistency and EXCELLENT driveability.
If the need arises, you can spray it up to a 350 shot of Nitrous (you never know). : )
We'll size it for the exact cfm range when it is on the wet flow bench to match your programs needs. But it'll probably end up being in the 830-840 REAL cfm range.
We don't pull off the shelf as each design is custom built to minimize or completely eliminate customer tuning requirements (we even try to set the idle dead-on for you).
Heres a link to some more info on this series: http://www.prosystemsracing.com/proseries4150.html
I hope to fire my engine up by mid-September.