4.9 is AWESOME.
Brings the gears closer together (?) while still maintaining OEM changes in revs between gears. Would be brilliant for 1.8 I'd imagine, as the 1800 has more torque than the 1600, enabling you to use the torque from the middle of the rev range, where I have to keep B16b constantly on the boil.
Was one of the best things to happen to my EK9, but I'm needing a close ratio gear set for the car now so my 4.9 is no longer needed. Pm me RVM if you are interested in buying it, it's a steal!