I had a Harrop OTR and changed to the Roto-fab. I just didn't like that you basically had to pull off the whole intake to clean the filter. I was thinking of going back to the stock or the walkinshaw 310 intake, or the k&n tube, but the Roto-fab came up on ebay. From the dynos, at the same place, but different times, the Roto-fab has very slightly more power/torque until higher revs where the OTR has a bit more, both probably because to the different conditions on the day. I couldn't feel any difference between the two.
I also have the full HSV340 exhaust.
If I was going to do it all again, I'd do the exhaust (good not large) and the tune first, maybe the intake tube. It's where you'll get the most benefit for real life driving.