If you look at the Jeff Lange spec sheet in the refrence section, the 91 repair manual shows 171 psi cylinder pressure, from the original 156, and 140ish or whatever the GTE is. That is where the spool and short term power gain is. That elevated cylinder pressure. But with less lift, you will lose out in the end. And with an 86.5-88 GE used cam, there probably is not any gain.