Same question as foxy85gt, but 4 an 82 GT
 

Hey everyone,

I have a stock 82 GT but in the works of a few upgrades. Edelbrock Performer 289 intake, Holley 600 (4160) carb, Edelbrock Flo-Pro air cleaner, 3/4" egr spacer (egr will not b hooked up), Tailor wires, cap & rotor set, plugs (help me decide please), Holley high volume fuel pump with new larger braided line and filter,double hump x-mem, Equal length shorties, 2.5" Mac o/r h-pipe, more to come, but at a later date.

The question is will 2.5" exhaust be too much for what I have? I don't want to sacrifice the low end, thats actually what i'm looking for! I was thinking of going with straight through mufflers but it seems the lack of back pressure will rob me of the low end grunt.

If this is the case, what should I do for mufflers? Can I reduce the exhaust after the h-pipe to a 2 1/4" set up to get back some back pressure?

All feedback will be very appreciated,
Thanks Jay.

wall:

For plugs, just use factory Ford ones, they work fine. As for the exhaust, yes 2 1/2" is too big for a mostly stock '82, just get a 2 1/4" cat-back and you should be fine, for straight through mufflers, there are some choices, Magnaflow, Bassani, Dynomax Ultra-Flow are a few, I'm running the Ultra-Flows, they sound nice, they're reasonably priced (there's a stainless version and a welded version, they may call them a "race" muffler for the welded version-welded ones are much cheaper), and they have lifetime warranty.

UNequal length shorties are better for low end torque. Equall length shorties rob you of bottom end torque. You say you want to keep bottom end performance so I would try to get a good set of 1 5/8 unequall length shorties with the full flange mount. I personally like the FRPP's because they are made of 409 stainless but they are also a little pricier.

Leave the Equall length shorties for the "Blown" cars.

But, if you are planning a lot bigger performance in the future, than you may want to stay with the unequall and not end up doing everything twice.

In this case, you will be better off, staying legal and buying a 2.5" CATTED H pipe [do they even make a 2 1/4" anymore?] and then going with a straight thru muffler and 2 1/2" cat back.

The car will idle nice, have a nice WOT growl, and the cats, believe it or not will actually HELP low end quite a bit being a source of backpressure.

Or, if you aren't rich, and have a buddy who has a stock 87-93 Take off H pipe in good working order, grab it, use some stock [hog them ugly welds out on the inside of each primary it WILL help flow] 87-93 headers, or buy a set of unequal 1 5/8 like mentioned and use them on the 87-93 mid pipe, then buy a good 2 1/2" cat back with a straight through design muff.

If you are going off road, and no cats, I would advise a chambered muffler so you have some backpressure. You are dealing with a 200-250 HP motor so it NEEDS some.

I've been low 13s @ 103 in 3 different efi 5.0s on stock motors and stock headers/H pipes.. going to an off road X pipe on the last 5.0 [a 89 notch] didn't to squat as the motor was stock... infact it lost a little in the 60 foot dep't.

I have since purchased a pair of Magnaflow 2 1/4's with 2 1/4 flow tubes. Next in line is a set of 2 1/4 tails. If this set up doesn't end up working all that great, i'll def take your advice.

Thanks alot, Jay. thumb: