H or X CROSSOVER?

When we tested crossovers, what we saw can't confirm or deny any scavenging, but we did see the engine (at the header collector) sensed less back pressure with the correct Dr. Gas X as opposed to the correctly fabricated H. We noted that with this effect, you could run quiet, (slightly more restrictive) mufflers with the X and the engine saw it the same as it did the older, higher flowing ones with the H.

The correctly fabricated X ALLOWS THE ENGINE TO SEE BOTH SIDES OF THE EXHAUST AT ALL TIMES. The incorrectly fabricated ones do not.

The biggest most important thing in all of this is that all Xs are not the same . In fact, some are worse than nothing at all. Dr. Gas did huge amounts of testing before 1995 to find what worked at NASCAR. We started with his test and components and found similar results on drag cars.

All the other Xs are not the same and so to be able to generally say one is better than the other is really tough. We know Dr. Gas crossovers worked, they made the tone change where it sounded quieter out the rear, we never saw more drone, and the car ran quicker and slightly faster. In almost every single case we used it, the same things occured.

Other testers, like we were and did, can only base their test results on the parts they are testing since all of the X crossovers and H crossovers are different. We worked with Dr. Gas and his did what they were advertised to do. And they sound cool as heck on all sorts of cars!