Torque cones will give you some needed back pressure, and lower the exhaust tone. Baffles will give you more back pressure, but make it quieter of course. Both will improve low to mid range rpm., more so with baffles. It's up to you. More power with baffles but quieter. Some power increase with torque cones, but louder.
Performance is always better if you incorporate the cross-over into your system.
Here's a trick that I'm using now on my Evo: I put cheap shorty mufflers on it that come with removable glass pack baffles. I took the baffles out, and the shorty's act like tuned expansion chambers with exhaust pressure building up inside, then spitting out the narrower exit. I couldn't beleive the increase in power, and they are pretty loud. When that thing hits 2-3k rpm you better be hang'n on. I cut off a pair of drag pipes to accomedate the shorty's.
Let us know how yer do'n Floyd...
Don't force it, get a bigger hammer.