I just got back from the dyno the other day, and while looking through my logs, I am seeing 1" of vacuum from 3krpm-4krpm, and 2" from 4krpm-5.5krpm, and 3" from 5.5krpm-6.8krpm.

I have a TPiS 52mm t/b, WS.6 intake, and a drop in K&N filter.

From all that I have read, 1" or less is desireable, so I am trying to find my bottle neck. My first thought would be the stock bellows, so I will swing by Home Depot to pick up the Fernco coupler that Fred seems to promote, but what would be causing all that restriction? My only other guess is the K&N might not be big enough.

 

My setup in sig pulls ~2.5" at wot above 5500rpms. I think my problem is the stock throttle body though.

 

i think you need a bigger TB. I believe your engine should start to build vaccum again after you're WOT.

 

Just put a blower on it. I see 0" at 1/4 throttle.

Seriously though, have you checked to make sure the blades are opening all the way at WOT?

 

Blades are opening all the way.