The chassis dyno will get you very close,we tune top running cars all the time and usually pick up some power which shows up on the strip in the time slips.the key is the weight of the drum never changes so there are no variables. if you don't change anything the runs will overlay within one or two H.P. if your tuning on the drag strip its hard to see 2 H.P. gain but on the dyno if you do several things that pick up two H.P. each you will see the results at the strip.about the only thing you cant do on the dyno is tune for traction on the starting line or converter flash.most runs need to be started at an rpm that is close to converter stall.find a chassis dyno near you that has a wide band A.F meter and you can get your jetting dead on,play with ign timing,valve lash different headers or collector length,engine trans and rear end oil weights and types and many other things,all without using up tires and having to wait for other cars to clear the starting line so you can get another pass.Bill