Dissapointing performance

Ok look. You keep saying you have "good attitude" but then we tell you whats wrong (small exhaust, small carb, etc) and you tell us we are wrong.

We are NOT wrong.

That exhaust is killing 50HP ALONE. AT LEAST.

No. I'm not kidding. Yes, at least 50HP. No, really, 50HP. YES exhaust matters THAT MUCH. Engines pump air. Period. If that air has no where to go, engine doesn't pump. Period.

That carb will probably give you great crisp throttle, but you're losing out on power. Period.

So I'll say it again.

2-1/2 inch exhaust. 750 double pumper.

Do these first. Then see what it reacts like. Figure out the engine before you start messing with converter and such. Which, BTW you need a lot more of.

Why are you fighting all these suggestions then saying you don't know whats wrong? If everyone is saying it, that MIGHT be what it is.

Oh, for your reference, he's my build:

340 .040 overbore
KB Pistons 10.05:1 compression
J heads - 2.02 Intake/1.60 Exhaust - bowl/port work (mainly cleaning up that terrible turn into the bowl) stock stamped steel rockers
Comp XE274H Cam - 230/236 @50 488/491
Street avenger 670
Edelbrock rpm air gap
Hi pro manifolds 2-1/4 exhaust with turbo style mufflers
B&M Torq master 2400 stall
3.55 gears

Builder rated engine at 380 horse with the manifolds. The thing ROASTED tires at will. Had 205's on there originally and it had no problem. But even 245's it could roast whenever it wanted. On the brakes, not on the brakes. Off the line. Etc. Now I'm putting on Hooker headers with 1-5/8" primaries into 3" collectors. Full 3" exhaust with Dynomax bullet mufflers and turndowns at the muffler. 4.10 gears. New custom PTC torque converter, 3000 stall. And FItech efi. I'm expecting to pick up at least 25 horse. But every desktop dyno I've done says anywhere from 30-40 horse. Once again proving, exhaust matters.