I did mine a couple times with the throttle body on using Wynns Car and injection cleaner. Did it with the throttle flap closed and then again with it open. Started it run and let it tick over a bit roughly at first and then blipped the throttle all good.
The next time I removed it, cleaned it again and used a flap sander in my hand held drill and ported it out a bit on bot sides being careful not to go to close to the flap. Refitted using gasket sealant and noticed a slight improvement.
The third time I did, I removed it again, took out loads of metal with the flap wheel again in the drill and knife edged both sides of the throttle flap. I also opened up the inlet manifold to match the throttle body. When I refitted it this time though I used gasket paper which I matched to the throttle body to ensure a good seal.
This time before starting I had disconnected the battery for an hour before restsarting. I am sure it felt smoother and I've noticed much better fuel economy too. Unsure if any REAL power gain, probably just smoother running as I've not done a before and after dyno run. Coupled this with the air box mod it feels so much better than standard.
Passed emissions too on the MOT no problem as well.
