This weekend, I just experienced the same problem. I have an '01 with a Banks exhaust and the Predator. I was hauling a trailer over the Grapevine and the truck went into limp mode consistently unless I babied it up the hill. I've climbed this mountain countless times with the Predator (in 40HP tow mode) and the trailer. This was the first time with the Banks exhaust. The code was "turbo boost exceeded." Must be a backpressure issue since the exhaust is the only new item.
I haven't tried going back to the stock tune yet but will. Funny thing is, I love the Predator tow mode for hauling the Grapevine and other hills and this is where I can't use it with this problem. I'll put a call into Banks and see what they say.
Phil B.
Correct Profile: Member # 6500, approx., Member since June 2001
2001 CC, SB, D/A Summit White