I did it back to back. Pulled the one set off, and slapped the others on. Both sets fit a normal car. Can't say what the merge alone did. The second (better) set was almost the same arragenment, save being about an inch longer on the straight out of the port, and much less angle leaving the port..

Something else just to try if you're interested. Wj ran an engine on the dyno without pipes in the dark to see where the flame actually went. surprisingly enough despite the angle of the port, the flame comes out almost square with the ground. I've personally seen power from a 32 degree flange head, having the tube be on 15 degree. Basically like you bent the tube up at the exit. You have to grind the header flange a bunch to get the tube straight, but it's worth it. The flame heads into the radius, instead of following the wall. Look at any PS header, and you'll see they all leave the port higher than the flange angle.

When I make headers I try to get 1 cyl volume
in before or at the first tangent.. and I make
them level with the ground... I dont know why
I do the level part of it.. I just think it
looks better

Buddy of mine has a set on his D/SA Demon. He said they are the absolute best headers he's ever had in the car.

Thanks guys, I appreciate the feedback.

People who know what they are doing can get vacuum with those. All I ever get is blowing in the crankcase because I'm doing something wrong. I had a guy tell me he's so good at it that after a dyno pull he can take out the drain plug and the oil won't come out.

I think everyone is in agreement that crankcase vacuum is a good thing that you need to try and achieve. Super stockers are looking for maximum power from their combination, I would ask some of them. Your application would even benefit more.

As suggested above a Star vacuum pump would be a good idea but probably not in the rules for you.

What you really want (and also not in the rules for you) is this.

very interesting subject we did back-to-back testing on my car at the last nmca race. The car was .07 quicker with the merge collector.. but makes 10 more hp on the dyno with the 4-inch open collector.. however this merge was built for my 3050 lb car with a two speed.. remember when going to a merge collector you have to add jet.. so I think like mr. P said it is Paramount that the collector is built for your Pacific combination

A properly done merge collector will pick a car up, provided it has a properly sized header to begin with. Both pieces need to be built for your specific combo, simply adding a off the shelf merge collector to an off the shelf header guarantees nothing.

Thanks for the replies, good stuff.

What about guys not on the West Coast? It's always hot and usually humid in Texas. Too far to tow to the West Coast.