Newbie question... I'm looking for a really fast motor for my 1/10 scale lightning stadium 10 4dw, while keeping things under a budget

I was going to go for an O.S. .18 CV-RX (about 28,000 RPM), since I heard great comments about it...

but then someone recommended an Ofna Hyper 12 !!! (1.4 HP and 37,500 RPM)

They both cost about the same, an the .12 has impressive numbers... but would the .12 really be faster in my truck? Perhaps I'm missing something here, but wouldn't the .18 still produce more torque and accelerate faster??
What confuses me is that the little .12 seems to produce the same or even more HP that the .18...