You're likely to have CEL's with LT's on the whipple tune, per Whipple on my last whipple build when I asked them. Get an aftermarket tune for aftermarket addons.
My Whipple tune was fantastic on my car, until I started with LT's etc on my last one.
My buddy tried the o2 extension things and it still threw the code. You can buy HP tuners and modify the whipple tune very easily. It is a very simple change in the tune.