boost went from 6 max to 3 1/2 max. What happened?

I haven't had a gauge on the car to check boost for a while. I put headers on & a high flow cat recently. I was getting 5-6 psi of boost when i checked a few months back. The car was stronger than ever so i never thought much of it. I ran my best time ever last week so it was probably the new mods that gave me those gains. I check today and i am only getting 3 1/2 at max. What could have caused the drop?

If you are saying that your boost readings dropped after the header and replacement cat install, this is typical as you "removed" some of the restriction in the motor (although you should double check your intake system to insure it is not leaking). As long as the engine performance didn't drop off, there is really nothing wrong. Pulley the blower up some (if the Powerdyne allows you to) and enjoy!

check your belt tension..

I had a similar problem with my powerdyne. Check your belt tension and check the rubber pressure tubes for cracks. I had to replace the fitting that seals the blower outlet to the upward facing pipe. Also if you used any rubber caps to cap off the pcv hole on the throttle body, check them to see if they got ruined by the heat.

-Pete-

I replaced the same rubber connection your talking about. The one that came with it is great big POS. The belt seams to be looser than i remember so i will redo it. It appears like it takes longer for boost to start meaning it will not reach as high. I found this from a year old post.
"I bought my car with the SC already on it and not much else. As it set I was getting about 5#'s of boost. When I installed the Headers and exhaust it dropped to about 3.5#'s. At the same time I installed the 9# pulley I put in the larger injectors with a MADZ tune. Thats when my boost went back to about 5.5#'s."

With the belt being more loose than it should be your boost will go up and down depending on the temperature of the belt. When it gets hot It'll expand and lose tension. When you first start up it will make more, this is how to tell when to tighten it up. This is the major draw back of a powerdyne kit, others have a tensioner pulley like you serpentine system. I've been thinking about fabbing up a bracket to bolt on a tensioner pulley.

-Pete-