Short of going FI, the manifold is the only significant gain you'll get. Depending on where you live, @Mike@TD.co.uk at Tuning Developments is a good man to talk to. TD sell the manifold, filter, and remap as as a fitted package for a very good price - likely to be less than doing it separately.
It was such a good deal that I drove 3+ hours and stayed in a hotel the night before when I had mine done. Lots of people here are running that setup.