I pesonally have never tried N2KTS, but it is basically the same as jack3d (you have probably tried jack3d I'm sure). Not exactly the same though. It is better. When I took jack3d I got too stimmed and I started getting wobbly at my knees during squats and I didn't have the best focus. But fom what I've heard of N2KTS, it gives a strong punch but increases focus. Also it is sold at NTBM so it is definitely a top quality product. Just message needtogetaas. He will tell you all about the product and maybe you could get a free sample out of him.
If you do end up ordering N2KTS, remember that if you get it from NTBM, and you aren't satisfied, you will get a full refund.
If N2KTS doesn't do it for you, try powerchews PWO.