OK I get 40 psi with the line off.And 35 psi with it on?

 

Cool, that's about what a stock, properly operating, fuel pressure regulator does.

I'd say "tune it", but you either need at minimum and air fuel guage [and after owning a wide band 02, the A/F guages that use the stock 02s are a guesstimate at best] or you can tap into stock 02 signal with a voltmeter which is much cheaper than buying a A/F guage for a stock type sensor... if you are creative.

SO..
Get a dyno tune, or go to the track [which would be real world results IMO] like mentioned, start off at higher pressure around 45-46 PSI [thats 45 PSI of "hose off" pressure - put it back on when done adjusting] as your combo will likely require it with stock 19 LB injectors which are good to about 325 HP give or take.. Make a pass, pat attn to MPH, and lean it out in 2 PSI increments. If the MPH goes away as you lean it out, put it back to where the MPH was at it's best... If MPH starts to improve, well, keep tweaking till you get that sweet spot... and don't do back to back to back passes. Cause it'll just get slower and slower.

 

Thanks Schlodes appreciate the help on this.................