There is NO ADVANTAGE at all on your std engine, the lower CR's are used as you can run more boost, but off boost effecienecy drops, so keep std CR unless you need to drop it.
If you want to make an amazing difference to response lag etc, get a DE SHROUDED head done, around £275, brings the torque in 500-800rpm lower, and makes it last 1500rpm further up the rev range, mine peeks at 330lbft at 2200rpm and has the same at 6500rpm, due to modded head.
tabetha