I had the head skimmed on my 85 SPG a few years ago when the head gasket blew and the head warped. My fuel economy and low end power have suffered ever since. The cams were retarded by a few degrees because of the head skim but it took me a long time to figure out that this was causing a power drop. The car ran ok but off boost low and mid range power was not acceptable for a daily driver. Power was also a little flat under boost until it reached the higher rpms where the power picked up and didn't trail off at redline. For a daily driver the lack of low end torque was unacceptable and just not as enjoyable. I installed DrewP's adjustible and indexable cam gears (http://www.saablink.net/forum/showthread.php?t=47799) yesterday. The indexing feature is absolutely fantastic. I was able to dial in exactly 2 degrees of cam advance to bring the timing marks to the stock setting. The car is now much more enjoyable to drive because it actually has some torque, and it requires less effort to get up to speed, fuel economy should also be improved. The cam gears are well made and precise and having the ability to index the cams precisely is what makes these cam gears brilliant. I would highly recommend these if you have the head skimmed. They should be fun to play around with too. Great work Drew!