Simply because of the 4 valves per cylinder...airflow, they are very capable engines, I've gotten used to DOHC engines with my neon....theres definately nothing wrong with a pushrod, but my car is going to be restomod...and since my 24v V6 (already converted to RWD and virtually ready to drop in)was stolen I have been debating which other engine I can go with, I keep swinging back and forth between an explorer distributorless GT40P engine, and a 4.6L DOHC engine....with my planned suspension setup of opentracker stuff(or global west, or control freak, whichever) by the time I am done with that and a rack and pinion upgrade, I'd be at the cost of a mustang II front end anyway, though a mustang II front end wont handle quite as well, it will allow me to use a mod motor...I'm not too worried about the "weaker" mustang II front end, since I would be reinforcing the frame rails with some tubing running to the firewall anyway, as well as some type of monte-carlo bar and export brace(whatever I would be able to fit around the engine) Sadly enough, one of the main reasons I want the DOHC 4.6L is I just love the sound of the engines(pretty much a v8 version of my 2.4L neon engine) I have seen some mustang II front ends with mod motors in 67+...not sure that I have ever seen one in a 66 though...I am pretty sure it will physically fit tough....