what makes a motor run? a spark igniting fuel. probably one of the most over looked things to give a motor good performance is the spark plug wire. The only kits i know of that come with quality plug wires is the ones Chris hill sells at
http://www.chrishill.myknet.org/ and also whizzers which motorbikemike has at
http://www.simpsonmotorbikes.com/. most of your cheap kits have a very cheap plug wire with them. if you have a need for speed start with some of the basics like a good plug wire. it will make a difference. i know when i changed mine it made a world of difference