i just did some testing using various cars of high and low stock hp as well as n/a and turbo. there was absolutly no difference in resulting hp due to order in which parts were purchased/installed. though, chrisdacuban may have had some special case. i did find out something that was new to me, however; the hp increase from the oil change also works after you've purchased parts and driven your car. for how long, i don't know, because i only drove a few meters.
