[jim_howard_pdx]

No Medic, you are cool!!!

I just hate the magazines because they do not test one item at a time. They just want to sell rags, so they go for the cheap and the simple. The bad thing, is that they rarely help someone make the best decision for their car.

An H pipe like mine is easy to work with. Disconnect the collectors and access to the drive shaft and tranny is excellent. On some X systems, the ground clearance is compromised, the ability to work on something else is compromised, and in the end is the extra 2-6 horsepower on a street driven car worth the hassles and problems down the road.

You should not think of your H pipe as a right angle. Air is almost identical to water in engineering terms. As the fluid (air) moves past the H tube it creates a vacume in that tube that pulls fluid from the other pipe. All this simple H pipe does is show EACH of the two pipes a vacume signal at all RPM ranges. This helps scavange the cylinders better. The improved flow is similar to increasing the diameter of the exhaust tube, but without the effect of raising the torque curve.

An X pipe and an H pipe theoretically should provide the same flow. As the exhaust expands out of the combustion chamber it violently pounds side to side along the pipe as it moves down the length of your exhaust. It literally "Rings" back and forth as it moves down the line. I think it is the reverberation of the exhaust pulses ringing back and forth across the 90 degree H tube that reduces its vacume efficiency. Since the X pipe shows a 45 degree angle to the reverberant energy it is less affected than the 90 degree H tube. I think this accounts for the .5-1.5% improvement in horsepower. To test this, you could have an H tube welded in at a 45 degree angle instead of the 90 degree angle. However I suspect that the exhaust guy would have you committed for insanity before they would weld like that.