I recently installed a downpipe & midpipe (among other mods) on my car. Since then, I've noticed a weird boost issue. My car does not hold boost at half throttle for more than 4 or 5 seconds. If I attempt to stay around 5 psi, after a few seconds, the boost will drop to 0 psi, and there's a very noticeable and audible surge in my exhaust pressure. Also, if I try to give it gas after the boost drops, it has a hard time boosting again, and sounds as though it's bogging out- no power.
However, it I give it 100% throttle, its holds rock solid at 11-12. I've checked all my couplers etc, and still can't find the culprit. Can anyone help me?

 

Anyone?

 

what are your mods?

how long since you changed spark plugs?

If your talking about half throttle and cruising, you wont get boost. Boost is a product of acceleration - if half throttle makes the engine stick at 6krpm, you will get full boost at half throttle at 2k, and it will only decrese after that as its not required. If when you hit 6k, your cruising, have no boost (normal) and then floor it and get no boost, check your vac lines. If you tell us your mods, what RPMs you are testing at and what boost levels you are seeing we can tell you waht lines to check.

 

My Mods are:

*Street-ported motor with 2MM apex seals
*Apex'i Power FC & FC Commander (RECENTLY, INSTALLED AT SAME TIME)
*Mazdatrix aluminum flywheel
*Greddy Airinx intake
*Greddy pulley kit
*Greddy Type S blowoff valve
*ASP Medium Stock mount intercooler
*3" stainless steel heat-wrapped downpipe (RECENTLY, INSTALLED AT SAME TIME)
*3" resonated mid-pipe (RECENTLY, INSTALLED AT SAME TIME)
*3" Racing Beat single tip cat-back exhaust
* "Supra TT" fuel pump (RECENTLY, INSTALLED AT SAME TIME)

I changed my plugs ~4000 mile ago with 9's in L & T

When at half throttle, I am accelerating, but unless I'm at WOT, or near it, all my boost gets bled off and I lose all power. I don't remember it doing this before I made my recent mods. Could it be something I screwed up when I installed the stuff?