So i just hooked up a boost guage to my 99 and im hitting about 15 psi... occasional spike around 16 if im lucky, and when its cold it hits only about 14...

i thot that with GIAC people were hitting around 17 to 18 and better? think i have a boost leak or is this typical? also, the boost fluxuates wierd between 2k and 3k about 2 psi up and down spiratically until 3k when it smooths out.

any ideas?

 

from what i have heard, 15-16 psi is ideal.

you probalby dont have a boost leak

you have a boost leak when you cant hold boost and sometimes you spike at 11 and rarely get to 15. then once you get to 15 it goes down to 10. LIKE MY CAR

you sound like your in good shape. but then again, that is just me.

 

If your looking to hit 17 or 18 get a n75 race valve. The reason why you only hit 14 cold is because the air is already more dense from the lower ambient air temp.

 

I hold about 17psi right now in cold weather. When its warmer out I hold 18-20. I dont really spike much at all ive noticed. I used to spike to 23 psi before I got my H valve.

 

n75 race and H the same? i know there are at least 3 different models. any loss in reliability or risk of problems changing the n75?

 

No there shouldn't be any reliability issues, the MAF and MAP sensor should make up for the difference. The n75h is less agressive than the race valve.

 

Some people go into limp mode with the J valve-its more aggressive. The ECS race valve and the H valve are the same thing.

 

Really, I didn't know that.

 

Why does the 97,98 lose boost throughout the powerband? I have giac with n75 also.

 

Neither did I until recently.. Ialwaysthought the ECS race valve was the same as the J valve. I found out its actually the H valve, so that was part of the reason i changed my sig.
Its pretty normal to lose some boost when you are WOT in higher gears, not 1st and 2nd gear though.