Runners and Headers?...Install or no????
Thread Starter
Senior Member
Joined: Jul 2002
Posts: 704
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From: Granby, Ma US
Car: 89 WS6 Formula
Engine: 305 TPI w/ some mods done
Transmission: Modified THM700R4
Runners and Headers?...Install or no????
Im thinking of getting a set of SLP headers, along with a set of SLP intake runners. My ? is........would this be a wise choice to make? I dont want to do this and have me lose torgue in the long run. Not to mention this isnt a cheap thing to do and i want to make sure it is somewhat worth it. Any thoughts on this???
Senior Member

Joined: Sep 2002
Posts: 988
Likes: 57
From: Nebraska
Car: '89 Formula
Engine: 355
Transmission: 700R4
Axle/Gears: 9 bolt
The answer really depends on what your goal is. Your best bet is to figure out exactly what kind of power you want to make and go from there. If you are planning on doing relatively few mods, a set of SLP headers ( 1 5/8 ) should gain you a few rwhp (more with exhaust as well), but most opinions on this board are that SLPs siamesed runners won't get you the results you want. I'd recommend AS&M large tubes. However, if you plan on making serious power (NA) in the future, get a set of 1 3/4 headers and ditch the long runner setup in favor of a converted LT1 intake or the like. The LTR setup simply can't support the airflow needs of a high-horsepower engine. Hope this helps.
I'd reccomend not getting any aftermarket runners until you've got some serious power mods and, unless you can get them used for cheap, the cost is worth it. I'd agree the AS&M runners look better, but you can work on the SLP ones and make them even better if you're so inclined.
I'll tell you one thing about the runners. After installing them and matching the plenum, I gained a good 500rpms. I couldn't feel any gains below 4000rpms, but it definitely pulls a bit harder and longer up high. The runners were the largest bottleneck on the engine, though.
I'll tell you one thing about the runners. After installing them and matching the plenum, I gained a good 500rpms. I couldn't feel any gains below 4000rpms, but it definitely pulls a bit harder and longer up high. The runners were the largest bottleneck on the engine, though.
Joined: Dec 1999
Posts: 3,544
Likes: 19
From: WI,USA
Car: 89 FORMULA 350, 91 Z28 Convertible
Engine: ls1, LB9
Transmission: t56, Auto
Axle/Gears: S60/ 3.73
the headers are you best bet. the runners I would stay away from till you get a cam or plan on doing the lower int. too.
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