Okay, so I'm about 135-140lbs, 5"8 tall...
Okay, so I'm about 135-140lbs, 5"8 tall and rock a size 7 boot. TRS BTX in 148 or skate banana 149? I pretty much ride anything and everything! also i noticed the skate bananas 148 is a narrow? what are the benefits of that and should i going with that instead of regular?
Well, obviously its going to be personal preference, but I would suggest going with the TRS. The TRS will be more stable at high speeds and slightly more poppy. You get that extra stability and pop from the C2. Adding that regular camber to the nose and tail helps load that tail and contact points so you don't feel too loose. The skate banana is a slightly looser more jibby feeling board.
To answer your other question about the narrows, the 148 TRS is narrow as well, so either way you'll have a smaller waist width. With a size 7, you would want a narrower waist width anyway. A narrower board will be faster edge to edge. That's the sole benefit, but an important one. You don't want to feel like your riding a sluggish lunch tray. Hopefully that helps.