You seem to be having the same problems I was when I had my 1.6 whipple. Instead of sticking it out I just sold it and got a turbo haha. Anyways I figured my missing boost was most likely a slipping belt. Even though the tension was really tight, I think it can slip- So I have read on here a guy scuffed up the pulleys with sandpaper and that worked. We checked for leaks, and pulley diameter research etc. Nothing worked but I never tried the sandpaper thing so ill never know. I had the high boost setup and was seeing 5 -6 lbs at 1400 ft and dry summer temps. At sea level it was seeing between 8-9. ( sea level had moister cooler air so perhaps that helped the pulley "grip" as I can not imagine 1400 ft difference would be two or more lbs difference!)Maybe that was just all the power it made and I was expecting more from the start.
