X & H pipe vs straight dual exhaust

Locomotion said
I went from open exhaust with collector extensions to a TTI X-pipe ending with Dynomax UltraFlo mufflers just in front of the rear axle and the car went faster by between .05 and .10. Headers are TTI 1 5/8"-1 3/4" step on a 360. May require minor rejetting.

It added an extra 60+ lbs to the car, but I removed the weight from other locations to bring it back down to what it was. You shouldn't have to worry about it since you plan on a full exhaust anyway. Room to swap out center sections is limited, but worth it. I plan on using their bullet style mufflers next time to save room and weight, although it may be a bit louder.

To me, X-pipe looks more effective than an H-pipe because not only does it help equalize the pressure between the two sides, but the flow from one side can help scavenge from the opposite side at the X as well.

I had similar results going from TTI headers (open) to a 3" X-pipe into 3" flow 40's and then dumps. Even with the added weight the 1/8 ET went from 7.25 to 7.20. I later added 8" long cherrybombs in front of the flows to take away the raspy sound. I love the way that exhaust system sounds with my 416.

And "one thing that sucks with alot of them, the monkeys that make them rarely debur the cuts before final welding wich looks like crap and might create alitle turbulence" I agree and used a round file to deburr the Summit X pipe so it could cross over better before the exhaust guy welded it all up.