The MT2 18ss is a fine truck - the upgrades make it stronger and avoid the usual problem with the truck which are centred around weak differentials. The kits aren't hard to build but you need to be patient and take time to do it properly. RC experience prior to building is a definite asset or you at least have to be handy and inclined that way to tackle it. I personally recommend an assembled version to start with but its doable otherwise.

I run a buku pipe on my K4.6 with great success although its expensive and requires more maintenance and tuning. I upgraded from the aluminum pipe to the Buku and don't have any other comparison for pipes to share - sorry.