I just got some 40 series with X pipe and 3 inch dumps. How much of a difference is the X over the H? I just got it off my buddy who just sold his fox body.
66P51GT said:X vs. H is negligible on a stock motor. With chambered mufflers like the 40 series flows, the h-pipe has proven to produce more power (2-4HP more than an x-pipe) on high-performance engines.
Mac True-Fit Long Tube headers have these dimensions. They are available from Dallas Mustang for ~$250.BlueMonster65 said:A street car with 300hp to 400hp would have long tube headers with 1 5/8" primarys and 2 1/2" collectors
BlueMonster65 said:the reason you want a small pipe immediately after the collector is to increase the velocity of the exhaust gas exiting the engine to promote cylinder scavenging.
BlueMonster65 said:General guidlines suggest 2 1/4 pipe for under 300hp 2 1/2 for under 400hp. what i am suggesting is that by mixing the pipe sizes a better exhaust can be created for a car working in that hp level of 300 to 400.
This is a KEY concept for most of the bolt-ons out there. Magazine articles and advertisements are all wasting our time and money discussing which one might have picked up 3-10 peak horsepower or foot-pounds here and there. The numbers you SHOULD want to see is average ones. A smaller pipe could lose 5HP at 6,000RPM but gain an average of 5HP all the way from 1,500-5,000RPM and be dead even from 5-6K. Which RPM range will you spend most of your time in?66P51GT said:You may pick up some peak HP but not sure there is an overall benefit. Average HP over the entire power band will probably be higher with the stock 2 1/4" exhaust.
66P51GT said:X vs. H is negligible on a stock motor. With chambered mufflers like the 40 series flows, the h-pipe has proven to produce more power (2-4HP more than an x-pipe) on high-performance engines.