I have had a lot of work done to my XX and talked to a lot of builders about them. They make in the high 30's low 40's stock. My XX is making 58WHP and 48tq right now with a HMF Optimizer, should be able to get a little more out of it when I get my PCV and switch my HMF exhaust for a better performing one. I also just order a few parts from White Knuckle Racing to make my XX a 727, I will post results of that when its done.