Way too many re-tunes going on with the facotry KB tune. One guy locally had about 320RWHP with the 9lb kit on the first tune. Had to go through two others before he got to 400. So that makes three trips to the dyno at $$$$ pre hour, plus time, plus the time and cost to send the chips back and forth. Yes, they have great customer service, Yes they will get you to what they advertise, but how much time and extra $$$ for dyno time do you wnat to spend?
After watching mast all the Mustang forums on the web about KBs for a year, I ended up getting the 9lb kit, but went for a custom tune right out of the gate. Had the shop that installed it get it right to begin with. Yes I know, "what about the KB warranty if you don't use thier tune?". I have full confidece in the shop that did the install, that they will warranty the system if I have any problems, so I not really worried. I ended up with 412/407 with car still hot, and the outside temp was 80 degrees, so there is probably a few more in there. This is with a fairly conservitive tune, as I am about 150 miles away form the shop that did it.
After watching mast all the Mustang forums on the web about KBs for a year, I ended up getting the 9lb kit, but went for a custom tune right out of the gate. Had the shop that installed it get it right to begin with. Yes I know, "what about the KB warranty if you don't use thier tune?". I have full confidece in the shop that did the install, that they will warranty the system if I have any problems, so I not really worried. I ended up with 412/407 with car still hot, and the outside temp was 80 degrees, so there is probably a few more in there. This is with a fairly conservitive tune, as I am about 150 miles away form the shop that did it.