Gotcha.. this is why the baseline runs are there though - to show a stock car on the same dyno, my car with all bolt-ons, and then bolt-ons with tune. It's not like I baselined 350 and then made 430 after tune. Many of those cars that 'struggle to get 400HP from NA' might hit it on that dyno because it's not accounting for losses from the rim/tire size and weight.
VCMPower recgonized this here http://www.m3post.com/forums/showpos...3&postcount=38
when the active cars saw difference in power when going from one wheel size to another. Minimizing variables is the key to successful dyno results. Not everyone is dynoing with the same wheel/tire size and strap down tension. A hub dyno elimanates both of those variables that can have an adverse effect on results.