I would save that bit extra for a K series as you will not regret it. OEM reliability for the same power as a "built" B18C.

K24 & 6 spd box can be had for up to about $4.5k (depending on condition and km's)

Swap parts, labour and tune approx $6-8k

Then later on down the track if you plan on chasing a bit of extra power, your dollar vs power gains (either by n/a or f/i) will be alot better when compared to a B or H series