With Macs: DA = -717 (55 degrees, 29% hum, 30.42 baro)
Pace Setter Long Tubes = +778 (72 degrees, 29% hum, 30.12 baro)

Macs 1/8 mile et = 7.072 @ 95.82 mph and a 7.103 @ 95.23 mph

Pace Setter = 1/8 mile et = 7.17 @ 94.60 mph

I did have two slightly better runs but was ET racing and had to shut down to avoid breaking out. Probably a 95.0 mph possible on the other two runs.

Althought quite a difference in Density Altitute, don't believe I gained much if any. I think maybe there could be some good gains if I had a better flowing cam.

No scale available but I did have more fuel so the car was slightly heavier last night.

 

THe only reason i went from macs to Pacs is because of my cam... ON a bolton car theres really no difference.

 

Wont really gain anything on the topend over macs, but you'll gain a lot of lowend power for the street. I have a graph from my car somewhere....peak rwhp gains from macs to FLP, 0rwhp. rwtq gains at one point, 40rwtq or so (like 2500rpms or so).

 

That temp diff from 55 to 72 makes a fairly large difference too.

 

True, there is nearly a 1500 foot difference in DA between the runs of the two headers plus the fuel level (roughly 6 pounds per gallon) difference.
The Pacesetters are giving at least some benefit over the Macs based on all of that IMO.

 

If this site is accurate I gain .2 mph and zero et.

http://www.stangbangerz.com/modules....h&file=density

 

I just bought Macs so thats good to hear.

 

I switched from MACs ory to FLPs (mostly for the ability to swap cats), car runs/dynos exactly the same. The FLP y-pipe is pretty crappy but no worse the the MACs I guess. I bet these headers/off road pipes/y-pipe and clamps weigh 25 lbs more then the MACs - these are some heavy headers and all those clamps (4 'v' clamps and 3 band clamps) add up. Not sorry I made the switch though, these fit up under the car nice and look a lot better then my old MACs and I can swap the cats out in 10 minutes which is a big plus for me..