Novak Explorer 2 max motor limit?

[Thirdgen89GTA]

Now granted I know that this forum loves brushless, however I'm not willing to spend the money for a BL system for this little TC3 I got for free. Came with a Green Machine 27t, Novak Explorer II, and a little 1500mah battery. I downloaded the manual and it says its good for mild modified motors, which to me sounds like a modified 19t, but does anyone think I can go lower?

Not looking for an expensive swap, just something to give it enough oomph to be fun in a small parking lot, but I dont' want to exceed the ESC's limits, looking for a motor that would work within its limits.

I'd rather save the money for brushless/lipo conversion on my 1/8th and 1/7th scale rally game cars. Stupid MMM needs to come out, which is what both of these cars are waiting for. I have the motor mounts from mike's store, just waiting on the systems. Look at the size difference between an IGT, and a 1/7th scale. They Hyper 1/7 is 735mm long nose to tail. :) 14" of room to play with ESC and battery placement.
http://home.comcast.net/~thirdgen89g...r17/h17_00.jpg
http://home.comcast.net/~thirdgen89g...r17/h17_01.jpg