Not enough boost!
 

So I hooked up a new mechanical guage and it's only hitting 14-15 psi.. On the stock guage I was getting 17-18psi.. I tapped into the line coming from top of mani for boost.. Pretty sure I have a vacuum leak around the manifold gasket.. Will this cause low boost readout on the new gauge?

what pulley are you running?

Or maybe they both read differently.

It's a 2.6 and it doesn't seem like it should be that far off

Could it be that the mechanical is more accurate?

14-15 psi is really low on a 2.6 unless you'd have ported head ,cams and free flowing exhaust.

I'd double check your connection at the source and the back of gauge itself.

what brand of gauge is it?

air temp and altitude can be part of it bad bypass actuator also

I've checked all the lines.. I bought some good line instead of the clear shit and it's the glowshift gauge I've got friends that use it with no issues

If you trust the gauge and your install then you need to check your by pass valve. Probably not closing all the way and bleeding boost

Thats the black thing on top of sc correct?? Also how could I check it

The valve moves easily on the bypass interceptor reads 16-17 on manifold psi