I have a powerglide transmission that is behind a KB Olds 526 w/ a PSI roots 14/71 blower in an automatic promod car. It was working fine for all of last year and beginning of this year but now when it goes to shift the rpm spikes while driveshaft drops then it recovers but seems to upset the chassis after that. I was thinking it all started after we raised the pressure on the trans to 275 back in may?? But Im really not sure. I have a psi sensor on trans and the pressure looks crazy! I am not familair with what the psi graph should look like but I would bet its not like this. Highest reading I saw was 304 I think?? I have checked the linkage several times. Had trans out and looked at by the builder. Looked fine but still does it. I have it set to shift at 7600. rpm spikes to 8200. If I raise shift point spike goes higher. I tried shifting at 8200 - it spiked to 8700. Car weighes 2650 1.flat 60ft, 2.79 330' 4.27 @ 171 with this happening. Need help!!