How much boost and vac does a stock 1988 tII produce? And what might it have after replacing air box w/ K&N cone filter and 2.5" downpipe, 2.5" connecting pipe w/ bonez hiflow cat., stock y pipe back?

 

stock boost is like 5.5 psi

After mods, maybe 8 psi...
You will have a nasty case of boost creep....I'd port the wastegate while you're doing the exhaust...

 

I've installed the upgrades and boost gauge and only get 5.5psi on on the gauge. The stock boost gauge shows quiker boost after the upgrades but is not accurate in pressure. My engine has only 57000. Is there a problem with my car? I am going to install a RB cat back system when it comes in and a fcd if needed. Should I be getting more boost?

 

I want more boost!!

 

Buy a boost controller.

Set it to ten psi and leave it there.

Make sure your fuel pump gets at least 12v at full boost with all the electrical things on, especially the lights and heater motor. If it's not 12v at full boost then do the fuel pump rewire..

 

I just took my car out again and put a little more foot into it and the gauge showed 7-7.5 psi. It ran smooth and pulled very good. I guess everything is ok. So a boost controller is next on my list. My fcd will be needed for sure and a voltage check on my fuel pump. 10 psi sounds good. I'll search for a good boost controller. Thanks for the input.

 

The S4's stock max boost is 6.6psi as per the FSM. This drops to ~5.5psi at redline.

 

try getting an FCD before getting all boost crazy. and get a real boost gauge.