Fuel pump blues (i give up).

Ok, long story short, ran on a stock mech. pump for a good 8 months, decided to step up to a better set up, so i found a holley billet HP125 for a great deal, install it, everything seems fine untill track time, the car runs slower, i installed a cowl mounted gauge, pressure drops from 7 too 4 under harder excelleration (but not WOT), so then i insall a carter street/strip mech 120 GPH pump, car is still off 1 MPH then it was with the stock pump, "dead headed" its putting out 10.5 psi, so as to not stress the needles i installed a holley reg. set the pressure at 7 psi, just under any moderate throttle or cruise it drops as low as 2.5 psi then drifts back & forth before going back to 7, so i raise pressure to around 9, its alot steadier & doesn't drift around, but at the track on 3 runs it drops as low as 3.5 in 1st., then in 2nd. going into 3rd. its around 4.5 & climbing, on the return road its back up to 9, at this point i'm just plain sick of this crap, WTF is going on, i also tried another gauge & the same ****, so thats not it, i am running a cell & 3/8 line all the way, theres no restiction, if i pull the hose off at the pump it poors out fast, i was told to just run the HP125 as a helper pump, & if i don't want to run it directly in line, run a Y so the mech. can still draw when the elec. is off, then turn the elec. on as needed, i'm thinking why should i need to go to these exstreams.

What really pisses me off at times (when its discussed) is all the "crap" said about the holley blue pump, Oh its a POS, oh it won't feed nothin, BUT for 2 yrs. i ran one on my 500 HP 451 duster running 10.8s @ 122-123 mph, i ran a 3/8 line ALL the way, includeing the feed from the cell to the pump, that car never mist a beat & pressure stayed "ROCK" solid at 6.9 psi all the way through the 1/4 on every pass, & i had at least 250 runs on this car, the only issue i'm concerened about is driving around on the "rotory vain" style pump with continous use & it getting too hot, but these pumps seem to really hold there own when it comes to holding pressure, plus i don't understand why this carter HP mech. pump would act like this..

I started this upgrating to be able to supply my nitrous & motor, but at this point i'm like FUK-IT!! I can't even keep the engine fed :angry5:

So please give me your in-sight on what you guys think, remember this is a very mild 360, not a damn rocket ship :munky2:.

I do have the outlet side going up to the reg. on the PS inner fender, then into the carb, is it possible its haveing a hard time keeping the lines full under WOT like this, could this pump be that much of a pussy, heck the HP125 is :-D. Rediculous.