And I quote "The 58mm throttle body in the kit is over kill for a 103" engine though. I'd sell that and have the stock 50mm modified to get the torque numbers over the horsepower. "
I don't have a kit but I would like to know about modifying my throttle body would I get to keep my cruse control and using the SE 103 CVO heads and SE 259e cams would I be pissing up a rope to have a brand new throttle body modified? One last question what dose modifying a throttle body pertain to, and keep it simple please?

 

You can have the stock throttle body bored,I am not sure if HPI still does the cable drive models but I am sure that Dan @ hotshot motorworks still does.

 

An un-modified 50mm t/body should work fine to obtain your goal, although I will add that we've used 55mm HPI's, even on 98" HO combos many times.
Scott