As far as exhaust is concerned, the SMSP 4-2-1 stainless header is certainly worth considering. Ideally, you want to maintain a constant exhaust diameter from the last collector back to the tailpipe.

To be totally honest, I'm not exactly thrilled about the test pipe on a daily driver.
I'm not going to shit a brick over it, but breathable air is rather nice.

That aside, I would be looking into Crower's #63402 cam for the B18C1, paired with their springs, retainers and cam gears. All VTEC B-series cams are interchangable. When dialed in and paired some form of tuned ECU to control fuel enrichment, you should pick up 15-18 hp off the cams alone.

As far as the throttle body is concerned, you're not at a point where it's a bottleneck. Given your plans, I would just as soon budget for ITBs.

Also, if you do go for an underdrive pulley set, either keep the stock crank pulley or be absolutely sure the the UD pulley is harmonically balanced, for obvious reasons. No point in making 2 hp at the expense of your main bearings.