I have a 2004 JCW it is stock. I recently just installed a boost gauge and im only reading 10 psi at the max. I always thought JCW were suppose to be more then that. Whats the problem? I did install the vac line into the fuel pressure regulator. If you have any thoughts let me know.

 

10.5 PSI is stock on '02-'04 MCS's. With the teflon-coated rotors, the '05-06' MCS's get about 11.5 PSI. The JCW comes with a 10-11% reduction pulley. The head is ported a bit, which will actually reduce boost (but increase flow, which is good). You should see 13-14 PSI. It's possible your bypass valve spring is worn out, or you have some other vacuum/boost leak. Check the seals on the intercooler.

 

Ok thanks. i'll look into it.

 

I'm getting around 12.5-13 psi of boost on my stock JCW MCS with 88,000 miles on it. Just as a reference......

 

I think it has to do with my elevation.. I went to California and ran 16psi with a 17% pulley. Back in Utah i am running 13-14 psi