[lincpimp]

Here is a though from the "maxamps hater":

For 45 min runtimes, 6s lipo will be a must and most likely more than 6000mah if you want to gear for 45mph+.

The neu 1515 is a great motor, and your best bet to work properly during a 45min run. I would choose the 2000kv model. On neu motors the max rpm they can handle is around 50k rpm (maybe more?). A 2000kv (rpm per volt is what kv relates to) motor on 6s lipo (22.2volts nominal) is turning 44400rpm, which is fine (with a high quality neu motor).

You should be able to use the stock muggy pinion and spur ratio, and the faster turning motor, compared to the stock nitro mill, will provide the extra speed you desire. However it is always good to gear lower during the first few tests to check temps and then gear up until you find gearing that runs well and does not overload the electronics. Electric will keep making power the more you gear up, but there is a limit when stuff starts to get too hot. Keep that in mind. Not to discourage you, as a much less powerful system than this will easily make a nitro motor (any brand) seem slow and weak.

The choice to use motor brakes, or mech brakes is your choice. Mike here at rcm makes a motor mount for the muggy that will allow both, but you will most likely have to fabricate a new servo tray to fit the brake servo.

If you opt to go with motor brakes, esc choice will be important. The quark 125b is only good for 5s with motor brakes, and may get too hot during those long runs. A mgm esc is the best bet right now, but the castle creations soon to be released monster max should also work well with 6s and motor brakes.

Not sure if a muggy has enough room to mount 2 battery trays, so battery choice may be difficut.

*CAUTION* here comes the maxamps hating part:

If there is one thing I can urge you to buy is good batteries. You have an ambitious project, and require the best equipment to reach your goals. Your batteries are going to determine the performance of your setup. Big power requires the best batteries, and Maxamps is just not the best. Neuenergy, Flightpower, Polyquest, or Polyrc are all made with enerland cells. Those are the some of best cells out there. Plus I do know for a fact that those listed mfgs have better matching processes than maxamps do (please do not ask how I know this, but I made effort to find this out for my own satisfaction, and have no reason to doubt my sources).

Most likely a pair of 3700 25c 6s flightpower packs wired in parallel for 7400 total mah at 6s will be enough to meet your goals. I am specualting here, as you may need more depending on how fast you want to go. Personally I would buy a pair of 5000 25c 6s packs and just run 1 at a time, for weight savings. It only takes 30secs or so to change a battery. More weight equals more load and less runtime, so you may need to go up to 9000 to 10000 mah total to reach your goal. You will have a heavy truck with that battery load

All in all it sounds like a fun project, keep us informed!