sup man,
I installed an obx tunable muffler as well. I've got the silencer on but opened up all the way. It sounds really really clean, even above 4k rpm. I don't take it over 4 that often though so It doesn't really bother me.
Anyways, My friend has installed 2.25 inch piping as well and what I noticed when in his car is that the muffler makes this really annoying sound after 3k rpm (it is taken to the max with the bigger piping) he didn't have a silencer on though.
The only thing I can suggest is to get a silencer (from the pic there is none in either one) and adjust it to your liking, it is real easy to adjust.
peace