shearers are bad ass pipes,
I had fast racing do a agressive dune port for my 4mil, I run 35mm carbs and R2 pipes, I have a +4 swingarm and it still stands up in 3 gears.
I would call Jeff @fast racing, Brandon@Wildcard racing, or Kevin@HJR, talk to all 3 and decide for yourself who you want to do your port work, they are all great.