I recently added some longtube dynatech headers,..with high flow cats,..with a y-pipe,...went to the track and my time was 13.8...added an x-pipe,..with 2magnaflows 2.5' pipes ...went to the track and my time was 14.3,..now my question is why did that happen if x pipes should give you more performance than y-pipes,... I did notice my wheels spining more, with the x-pipe,..should I add some cut-offs,..or should I go with 3' pipe?

 

Well true duals have never been proven to add more hp same with anykind of x or h pipe. It's mostly there for sound purposes when you do that. I've had both setups and enjoy the sound of the true dual setup but the gains on both styles shouldn't affect your track times that much. How many runs did you do each, weather during the runs, reaction time, etc... I don't think track times are an accurate judge because of all the different variables. Dyno is really the only way to go when making small changes like pipe size adjustment, crossover pipes or hilfow cats. When I go to have Troyer install my, well everything, they are going to add a 3" midpipe on the dynatech headers which will lead into a 3" cat back setup so I'm sure it's got to account for something, especially more airflow.
http://www.ford-trucks.com/article/i...tallation.html

 

Its because you went with true duals. Single exhausts are the best performing exhausts for these trucks. 2.5" true duals are too open, they'll only sound good. If you want true duals to work you'll need mandrel bent 2.25", or go back to a 3" single with a muffler of your choice.

 

when you go true dual you open it up too much, losing the scavenging effect and back-pressure. and there for you lose torque and hp

 

Theres so many factors as to why the times are different! Air temp, track temp, humidity.....etc etc....I wouldnt blame it all on the exhaust! Dont see you losing a 1/2 second from exhaust changes...

 

could it be something as little as a bad launch with too much wheel spin?

 

Do you have a CAI and a custom tune to compensate for this newly found air flow?

 

This makes a lot more sense if he told you he had a twin screw blower.

 

true duals aint helpin

 

There's a great reason right there why your times are slower...

No kidding right!? There are SO many different variables that could have caused the difference in times. Funny how everyone yells exhaust. If anything, the 2.5" duals and x-pipe are going to help at the very high, WOT RPM range... Like when you're running WOT down the dragstrip. Get the thing on a dyno to really see what's going on.