To tell you the truth you will not see 185bhp without spending alot!

As far as i know keeping it a 2.0 you will need Jenvey ITB's or similar and standalone management.

I think 170 can be achieved by changing round the bottom end for a 2.3 galaxy/scorpio one but that involves some work on the block to mount to the 2.0 RS head and also the RS sump.

I have got an RS2K myself atm.