how much performance do you guys think I could be loosing by having to use the adapter spacer on my box stock Trick Flow manifold on the 512, kinda looks like a bit of a choke point to me,, oh and it has been blended to match the manifold opening.

Bill I've been told it's worth some gains don't remember how much but that's what I was running on my car

Was told that by just about everyone back when I had one on my smallblock, increased plenum volume was the reason they gave,, just wondering if it held true on a larger cid engine that pulls more air.

It was INDY that was quoting about 12hp gain

I have pics of my fully modified/ported Victor w/the 2" adapter on FB and the gains are there IF you blend it into the plenum and runners.............

My thoughts would be if your engine wants a shorter runner than a big plenum dom flange would be helpful.

Here's another datapoint: our 451 RB with a set of stage VI heads, decent size roller cam, 1.5 rockers and an HP 950 made 620HP. We replaced the 1.5 rockers with 1.6's, and an 1150 Dominator atop a 2" adapter with some nice blending made 677HP. I remember the dyno operator looked at the adapter and said "that's not going to work". I'd say it didn't hurt!

I have dyno tested two different M1 intakes on the same motor the same day, one 4150 with a 2.0 inch tapered Dominator adapter with a Holley 1050 9375 non HP 1050 CFM carb., swapped the intake to a M1 4500 flange intake with no spacer, the motor lost right at 8 HP, I then added a Wilson 1.5 inch four hole reversion spacer and picked up a little more than 10 HP with no other changes on either test.
Adding plenum volume will normally make most BB Mopar motors gain power
I've seen the same results on another car at the track that swapped from Team G 4150 intake with a tapered Dominator adapter with a dominator carb. to the same brand, Weiand Team G with a 1.5 inch open spacer and his car went faster with the 4500 type intake and spacer compared to the 4150 intake and tapered adapter with the same carb with no jetting changes

I have always explained it like this. If eight guys are drinking beer from a keg and you make the keg bigger, eight guys are going to be much happier.
Todd

Now that's a explanation that I can relate to!LOL
sounds like it should be ok for now or untill I can come up with some thing better.

Bottom right hand corner of this page (hemi):

http://www.indyheads.com/images/22.cat2014.pdf

And this one for Wedge:

http://www.indyheads.com/images/10.cat2014.pdf