hey i had thought about this before and was just curious... i measured the mm diameter of the holley unit from the top of the bores and it was 55 mm's across which is = to 2 & 1/8 th" the stock tpi is what 52mm x2 so the holley should flow better right.
now also i have looked at several aftermarket tb's for the tpi's and the throttle blades are way down in the bores and the air has a straight shot going into the bores, now this may be why tbi gets a bad rep becasue if you stuck 2 big injecters into the tube that was on the tpi unit it would block alot of flow.
i think they must not be a big deal as some people may think becasue with a flat based filter pan or one like mine that smoothly tapers down into the tb it is able to draw alot of air from the sides thus bypassing the injector pod becasue the air comes underneath them. plus the holley unit starts at 2 1/8" but it tapers down into 2" so it creates a little more velocity going in.
kindalike a venutri. i had an aluminum ring on my 90 300zx in the intake that has a dyno proven 10 hp increase by speeding up the incoming air. also when i was running the carb i bought the stubb stack which in a recent mag article was shown to add anywhere from 4-8 hp over stock from a $40.00 hunk of plastic. i used it and it was hard to tell if it made a diffrence or not but every little bit adds up. if we could come up with a "stub stack" design for the tb i think it would help a little but it could also cause problems becasue it would change the angel of the incoming air to a steeper angle which might increase the resistance from the fuel pod, what do ya'll think. i still would like to spend the 40 bucks on that aluminum power charger to see if it actually helps. if it supposedly adds 10 hp then it might add at least 5 hp and who knows using the holley unit might net a little more power. it won't be a waste of money if it adds at least 5 hp. at least in my book. i have to still sell my edlbrock 600 cfm carb and the edbrck stubbstack piece, maybe i'll use some of the money to buy it.
my only concern is that it won't fit under my hood.
i have the ss hood which nets a little over 2 inches, but i am using the performer rpm with a 1" spacer and the tb adapter the direction say in fits under the stock air cleaner but what does that mean exactly... does it sit inside the filter or is it 14" at its top and the 14" filter sits on top of it? if so then it will be a tough fit. i would probobly have to go with a 2" filter instead of 3".
well any comments?
also this is just some thoughts so please no flaming...

 

car craft tested these parts on an old 305 tbi pickup truck the power charger made 8 hp and 8 trq ... hmmmnnn


Power Pulls
Configuration HP TQ
Test 1 baseline 140 @ 3,850 200 @ 3,850
Test 2, after-cat exhaust, tune-up 168 @ 4,100 229 @ 3,800
Test 3, above w/headers 167 @ 3,500 237 @ 3,500
Test 4, above w/Hypertech chip 176 @ 4,050 260 @ 3,300
Test 5, above w/Power Charger 184 @ 4,100 268 @ 3,400

Total improvement 44 hp 68 lb-ft
Percentage gain overall 34% 34%