Hi Fatboy.
If you just want more gain out of the TA but no tonal change just go for a clean boost pedal. I got very good results when I had my TA with a Sparkle Drive with the mix knob set to clean and the volume knob set close to max. But there are a whole lot of clean boosts in the market, some change your tone a little some are totally transparent so take your pick. You can also make your your own, there's a truckload of schems floating around the net of commercial and DIY devices.
On the other hand, if what you want is a tonal change then you should be more specific. Different pedals change your tone in different ways but many people like tubescreamer type pedals with thier boogies. I don't, I think they have quite a lot of mids already to bring more into the mix with a tubescreamer, but it's all a matter of taste after all.