Keep in mind that the overall hp numbers they give you are for dyno runs only. They don't measure what kind of horsepower can be sustained on the street, like when towing your toyhauler over the Grapevine.
I have not been able to get anyone to commit to an actual streetable horsepower number when it comes to the 66 or 62.
I can tell you from experience, any more than 430hp or so on the street with my SPS66, Banks Technicooler, 4" turbo-back exhaust (obviously no cat), and an AFE stage II will give me EGT problems right quick. I'm talking 4th gear roll-on, and the TST will defuel before I need to shift to 5th. At the settings that netted 430 or so on the dyno let me run the 1/4 mile without the TST defueling at 1400°. The highest settings I can run---TST twins set on 6/2 with 50% on the MP-8.
Anyone with a SPS62 and some dyno time care to chime in? I'd like to know what settings you're using for towing (and playing) and how that relates to your numbers on a dyno.