70 MACH I

I'm sorry my friend, I tend to disagree with your statement:

"You lose low end torque when you open up the exhaust on a stock car (especially 2 valves which already suffer in the low end torque dept). "

Most two valve engines put out excellent low end torque, (that's why they are so commonly used in trucks) 2 valve engines tend to suck on high end HP due to lack of breathing. When Ford put the 4 valve mill together in the Lincoln Mark 8, they actually created an intake controlled by the PCM to choke off intake runners to generate more low end torque. I don't know what they did with the Cobra, but I have noticed they are not that torquey off idle as compared to (Cobra guys step in) a 2 valve GT (both Stock of course) Many manufacturers have tried to address this in different ways, (the Honda VFR motorcycle uses VTEC technology to snuff two of the four valves at low RPMS. The ford Boss 302 with it's huge valved 4V Cleveland heads was a teriible driving car with the stock 3.55 gearing, 4.30's woke them up. The goal of every GT owner to improve performance is to improve breathing, every Cobra owner as well, but they have to be a tad more careful on low end torque or they'll have to launch at a higher rpm/or gear down as many do/ or utilize FI/ to initially accelerate quickly. Despite all, if cost weren't an issue, there would be a Cobra in my driveway.

MustangMafia

From what I've heard, an aftermarket H will not hurt nor increase torque, and an X will increase it a little bit. This is because with the X, the exhaust gasses are forced into the X design no matter what the RPM. Whereas with H pipes, the gasses can go either into the "H" bend or just straight through to the tailpipes, which wont offer as much backpressure. Somebody please correct me if I'm wrong...

bluepony4.6

The goal of every GT owner to improve performance is to improve breathing, every Cobra owner as well, but they have to be a tad more careful on low end torque or they'll have to launch at a higher rpm/or gear down as many do/ or utilize FI/ to initially accelerate quickly. Despite all, if cost weren't an issue, there would be a Cobra in my driveway.
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Basically this is what I am trying to say. I lost low end torque when I went from a factory h pipe to a catted 2 1/2" x pipe. Although it was only 6 lbs, it was still a loss. I picked up 9 hp though. The only time I've seen an exhaust mod really add more torque is when long tube headers are added to the equation. Aftermarket BBK shorties have been shown to actually lose torque.

Remember we're talking about a stock 98 2 valve with no tuning and is already suffering due to inferior heads, 99-04s have an advantage due to the PI heads and cams. When you take the cats out of the equation you lose critical backpressure which helps in the low end torque dept. I look at my dyno sheets and I see that my ride lost some torque down low but picked up torque at higher rpm.

From what I remember the junction in h pipes were designed to even out the exhaust pulses more than for performance. X pipes even out the pulses but don't interrupt flow as much as h pipes so you gain hp.

MustangMafia

Yea they were designed to even out pulses. The X pipe does this better because no matter what the RPM, the banks of exhaust are forced to collide with each-other due to the X design. With the H, the exhaust isnt forced to intermingle at higher RPM because some of it will contine right on through and out the rest of the exhaust system.

70 MACH I

I can understand how BBK shorties can reduce torque. I was amazed at how they were made. I bought a set from another member this week at a good price. I'm retaining my stock catback, rear pipes, and have hi-flow mufflers installed. What I was amazed at however was the construction, 1 5/8" pipe, but with the welding inside the flange, they are necked down to 1 3/8" in spots. I spent 2 hours with a die grinder restoring the openings to the nominal diameter. I too, was concerned with shorties, but I reasoned, they were installed on all the EFI fox mustangs of the eighties by the factory, those 5.0's cetainly did not lack for torque. This setup is still predominent on many Ford products. Time will tell, my intentions and goals for my car are modest, hopefully with the stock H-pipe and rear exhaust pipes, I can attain a decent torque/HP balance.
John