I put together a mechanical wastegate that was designed after the Heath diesel system. I originally tried a 12# spring and found that the max boost I was able to generate was about 1.5 lbs. So I replaced it with a 24 lb spring and I was able to generate about 7 lbs under about ¾ throttle, but when I went to WOT the pressure dropped to about 2-3lbs . Any suggestions on how to correct this. Or is this how these systems work?