The lack of a muffler baffle makes zero difference to the TT 46 Pro -- it has a excellent carb & it can even pull fuel a reasonable distance without any muffler pressure at all. The piece of wood isn't going to cause a problem unless it is right up close to the muffler outlet & largely covers the outlet. The fact that you think that the power is low compared to your OS suggests a tuning problem -- the TT Pro should be indistinguishable from either an FX or AX in power.

As suggested, check the plumbing, the plug, & the mixture (both high speed & low speed).

Additionally, is the cowl open enough for adequate cooling? You may be overheating.