When you say you get it up to 6 in park are you talking for a split second or can you hold it at 6 pounds? You shouldn't be making any boost while in park because the engine has no load on it, because it’s not in gear. My Radix will show a few pounds right at start up if I have my foot on the gas but then drops back into vacuum almost immediately. If the belt was slipping I think you would hear it. If your blower is set up to make 6 pounds you really wont see 6 until you are at WOT and near redline, right as you shift into 2nd or 3rd.

 

Yes, I can hold it at 6 while in park. I do still have a stock exhaust, which is being replaced next weekend with Thorleys and a magnaflow cat-back. Anyway, back to the discussion -- at WOT the most I can squeeze out is about 4 psi. One more thing I'll add, though, is that I have no intercooler and it's been 95 degrees every single day since I've had it on.

As I said before, the truck hauls ***. Maybe I'm worrying about nothing?

 

this is typical of a centrifuge type blower or turbo.
what the root's guys cannot under stand is that we can make boost while in park or in neutral.
at what RMP do you make 6 psi while in park?
and at what RPM are you at during WOT to be making 4 psi when you look at the gauge?

if in park, with a rev up to 6000 rpm's and make 6 psi will not be the same as
driving down the road and hit WOT and look down to see 4000 rpm's and 4 psi of boost.
if you want a higher boost number at a lower rpm you need to put on a smaller pulley.

 

Well, mine's a twin-screw, so I think I'm more along the lines of a roots-style. While in park, I can get it up to 6 at around 5,000 RPM. Driving, if I floor it it gets up to around 4 by about 3,500-4,000.