The most important thing is that you get catless midpipes, the brand is not that important.
RPI gives the most whp,but sounds like crap with stock mufflers (like a 2 stroke engine)
If you have a more restictive midpipe= more mid range torque, a little less hp on top.
Less restrictive =more power on top,a little less torque midrange.
M3 E92 ESS VT-625