2nd to 3rd PFFFFT!

So my exhaust finnaly shoed up today, too bad it was not the one I ordered. I ordered the Flowmaster Force II and got the American Thunders. Oh whell I put them on anyway, and with the BBK H-pipe the sound is awesome (sorry, eighties flashback) Nice deep tone and very subdued when I am not on it. The problem is now when I shift from 2 to 3 at higher rpms, or when at WOT it makes a mellow pop, sounds like PFFFFTT. Well close anyway Is this normal with an o/r h-pipe, or a trait of the Flowmasters?

Yeah, I have never had good luck with Jet Chips anyway. What would be a decient tuner for it? I cant afford an Anderson PMS or any of the big buck tuners. Would the Hypertech be OK, I would like to use a Predator but dont think they made them for 96's
Any input would be helpful.