First, understand what you want out of the motor, what you're looking to spend, and how fast you want to go down the quarter mile. Understand what kind of tradeoffs you want to live with day in and day out, then go from there.

Personally, I've seen good results with a simple B16A in the DA's, simply because the car is pretty lightweight. B18C1 would also be a badass setup. Doing a B18C5 is something that doesn't make economical sense to me anymore, IMO. While the overall install costs are WAY cheaper than a K-Series, getting a K20A2 and a B18C5 are only about $1000 apart now.