Hello mickm,

What Mr P body is saying is that if your gauge reads high psi then the 0.5 psi reading is likely not accurate. Gauges should read about the middle of the psi expected for best accuracy. So in your case a 0 to 1 psi gauge would be ideal. Unless you have a very high reading gauge it is likely not a problem.

There is another problem I ran across that simulates your conditions. My exhaust tubing was inserted to far into the reducer creating an unintentional reversion cone. This caused a relentless back pressure problem that went away when I had it re-welded into the correct position. Just another thing to check. Good luck.

Damon