I recently finished my header and exhaust install and like everyone, expected a gain from it. What I got was three strange problems that have me puzzled.

A. When you punch it at low speeds, the car hesitates bad, then picks up after a while.
B. Sometimes the car backfires when I let off the gas.
C. The car is slower. I spent $700 and about a week on installation and the car is slower.

Anything you guys can to do help is appreciated. Thanks.

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'83 Firebird 2.8
'89 Firebird Formula 350
Red/grey, t-tops, and a 3.27:1 rear
K&N, TB bypass, no MAF screens, CAI, full Accel ignition, no cats, Hooker Supercomp shorties, Hooker 3-inch catback

 

have you had it at a track to tell it's slower? if so it may be the weather conditions. is the o2 senser hooked up? have you changed the timing? you might want to make a small adjustment there. didn't unhook a line or wire while you were doing the swap to headers?

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ICON Motorsports

1st & 3rd
MM Black Diamond 538 F&AM

 

I have SLP headers, a hollow cat, and a flowmaster cat-back system. I have the same problems you're having, and it's cause I got an exhaust leak!! Are you also running rich? Listen for a clicking noise, since that's a sure-fire tip off of an exhaust leak near the headers. Go under there and tighten up all the bolts you can. Should fix it right up...

 

Sounds like what happened to my one friend who owned an '87 GTA. Did a full 3" exhaust on it with SLP headers, and eliminated the cat. Result? Back-pressure got too LOW. Car dogged out at low rpms, acceleration was sloppy until about 2,500rpms and then it picked up.
I don't know if you eliminated the cat or not, but low back pressure is sometimes not a good thing. Also like ede said make sure your O2 sensor is still present/functioning, and you may want to advance the timing by a degree or two. My L69 ran like a slug with my 3" exhaust until I advanced base timing to 4*, now it's all better.

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DR Stevens
1984 Trans Am 305HO L69
sucks gas, hauls ***
1991 Firebird 305 LO3
for days when I need a/c

 

Thanks guys!

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'83 Firebird 2.8
'89 Firebird Formula 350
Red/grey, t-tops, and a 3.27:1 rear
K&N, TB bypass, no MAF screens, CAI, full Accel ignition, no cats, Hooker Supercomp shorties, Hooker 3-inch catback

 

had SAME problem 6 and 8 wires were crossed.

 

Yeah, recheck the firing order and be sure no plugwires are shorted on the header tubes..........