I got a M45 on my 96 Z24. The kid I got the M45 from said he was getting 6 pds of boost on most days on his stock sunfire. Im only getting like 3 to 4 at the most. Im running a stock crank pulley. I also have a small port and polish on the head. Im running a 62mm TB on the M45 with JBP stage 2 cams. Also got a header and 2.5" exhaust all the way back. So I have plenty of air going in and out.
What could be the problem???

All of your breathing mods are whats causing the lower boost numbers. Roots blowers need back pressure to keep the psi numbers up. IF your car was stock like the previous car the blower was on the numbers would be the same. The psi shown is only realitive to power. Your more than likely making more on 4.5 than he ever did on 6psi

x2, PSI is not what your looking for, its power, and more flow=more power but less psi on the guage. I think I was seeing 4.5 when I had my stock pulley on.

worry about whp and boost pressures.

If you can make the same whp with lower boost pressure, you're better off.

ok thanks guys i was worried something was wrong