But just to confirm, it does fit both tfsi and tsi engines
Sorry, but I have to strongly disagree. If it were to fit the TFSI, then it would DEFINATELY start with 06F. VAG part numbers are not 'forwards compatible'. 
EDIT: checked ETKA - it categorically is NOT listed for any TFSI engine. It ONLY fits the TSI engine which has a completely different make of turbo!!! 
So are you telling me 100% it wont fit and may cause damage because it seems lots of people have already made the change and the results seem very good. My dealer tell me the system is being updated to show this as the latest replacement, my specialist are telling it will fit fine and companies like ecs for example are selling it to fit all tfsi and tsi engines. see link http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi/?html=learnmore.html&productID=259456
I am also told the early tsi's have revision g also so if both fit to that then both must fit to the tfsi??
I'm apprehensive now because mine is being fitted thursday and dont want any adverse effect
Hmmmmm, righty - let us try and clarify this.
Firstly - will it physically fit? It very well may actually 'bolt in' and connect up to the electrical plug. But physically 'fitting', and working correctly are two very different issues. As I previously stated earlier in the thread, that valve as described on the yankie site is categorically not for any TFSI engine, nor is it for any K03 or K04 turbo.
Secondly, part number ordering:
VAG have a very clear and well established method for their part numbering system. Take the Mk5 Golf as a whole. It has a "typ code" of
1K - and all parts developed for a Mk5 will usually start with
1K0. For specific right hand drive parts, front windscreen wipers and headlamps being obvious examples, they will start with
1K2. Now, the Mk5 may also have some parts which have been developed and used on previous models - and another specific example would be the rear brake caliper piston seal set - the Mk5 part number is 1J0 698 671 - but the "1J" bit indicates that the part was originally fitted on a Mk4 Golf. But the opposite way isn't true - you can NOT use any Mk5 "1K" parts on an earlier Mk4 "1J" car.
Now, understanding the above regarding the whole car numbering system, you need to be aware that major mechanical components also have their own part number groups - which mainly mean engines, gearboxes, and rear axle final drives. The 6-speed DSG gearbox has a parts group of "02E", a 4.2 V8 petrol engine has "079".
The Mk5 GTI 2.0TFSI engine has a parts group of "06F" - and most of its part numbers will begin with 06F. It may also carry over some parts from earlier engines, such as 06D. But when any parts for the 06F engine are revised, they will ALWAYS begin with 06F. Now, if a newer engine is developed, in this case the Audi valve lift TSI engine (06G) - any new parts specific to this new engine will begin with 06G. But just like the cars, these 06G parts are NOT compatible with previous engines (the 06F in our case).
So, at the end of the day, the part in question may well bolt on - but it probably will NOT work correctly, because VW never designed it to fit that particular engine. So, if you want to carry on and have it fitted - well that is your call - but just be prepared for things to go wrong - and be unable to work properly.
HTH

EDIT: and having a quick look on ETKA - no TSI engine has a G valve!
