i dont know what to buy for losi 8 buggy..

[SpEEdyBL]

The 1512 1800 will not be slow on 4s. Don't be afraid to use to use pinion sizes in excess of 17 teeth. On my tekin 1900 kv (pretty much the same motor), I gear 13/46 for a 80x50 foot track and nobody is faster than me on the straight. In other words, the acceleration curve from 0-30 mph is just as good, if not better than any other motor i've seen. 15/46 is dead even with nitro on a 150 foot straight. One of the greatest benefits will be the long runtimes and low motor temps. And yes, 5s and 6s is great fun!