OK, having had the boxes in for a couple of weeks I thought a bit of a review might be useful.
First of all, the ordering process from DTUK was very painless - they were very helpful on the phone and dealt with some queries I had as to the location of one of the connections on the engine very rapidly. A member of staff with experience of fitting units to the GTI was made available to me for support on a Saturday if I wanted, outside of their normal opening hours, though I didn't actually need this in the end.
I ordered an FSR as well as a pedal box. The latter comes at a discount if you buy an FSR and I'd read enough good comments on the internet to want to try one out. The units arrived by recorded delivery the next day with everything correctly included and preconfigured.
I had timed the purchase to coincide with the renewal of my insurance to save on any fees for modifying my existing policy, but I didn't have any time to do the installation on the weekend of the renewal. To work around the problem I installed the units and cable loom a week early and then (once I'd checked that the car ran OK) took the unit back out and replaced it with the blanking plug that goes on the end of the cable loom and effectively returns the car to its factory state.
This meant I had a week where I only had the pedal box in (as this is does not need to be declared on the insurance) which gave plenty of time too see what difference the pedal box made on its own. Long story short - if I couldn't afford both units, I think I'd have the pedal box. Even on the stock car, it makes it much more fun to drive. The car is no more powerful, but it's a lot more responsive and it really shows how much potential there is in the car that you don't get to access day to day because it's hidden away at the end of the throttle travel. After driving around with the car on mode 2+1 for a few days going back to the VW standard 'Comfort' mode makes it feel like the throttle has a big pile of cotton wool in there somewhere.
Installation of the pedal box is less intimidating to a non-mechanic, but arguably not that much easier than the actual FSR - you have to work in a very constricted space in the footwell, and the latch to release the connection was extremely stiff and in a position where using any tools to help was very difficult. Now that I've got the pedal box in I'm actually not sure I can get it to release again - but this could be due to a manufacturing variance on either my car or my box.
Installation of the FSR cable loom is fairly straight forward if you take the time to read the included instructions and the other forum posts on here and other GTI sites. Having now done it, I agree with those who were giving me advice higher up this thread - you definitely want to jack the car up unless you're very confident you know what you're doing. I might be able to do it from above, but the prospect of undoing a connector and then perhaps not being able to reach to reconnect it made me decide to put the car on the jack. (The hardest part of which is finding a position, especially at the front of the car, where both a trolley jack and an axle stand can be used simultaneously - still not sure I got this entirely right and I wouldn't want to have the car jacked up for a long period). Once the car is lifted enough to get a look underneath it's just a case of removing 9 of the 10 screws on the protective panel and moving it aside - relocating it afterwards is very easy because it clips in place before you add the screws back for support.
To put the above in context, I know nothing about car mechanics and even the idea of jacking the car up had me reading around on the internet extensively to make sure I wasn't going to put a jack through a non-loadbearing panel or drop the car on my head or something - if I can do this installation, anyone else who can tie their own shoes can probably do it.
So, first impressions of the FSR over that first week of driving to work and back while commuting, with occasional clear B road/dual carriageways but reasonable traffic, etc...
Not that special really. I thought it made the car sound different, which was an improvement, and it does feel more powerful - but only in that 'I could be fooling myself because I just spent hundreds of pounds on this thing' kinda way. (Just to keep banging home the point - the effect of the pedal box is IMMEDIATELY apparent with no 'am I imagining it' soul searching required!)
However, this weekend I had a trip to North Wales, which from Bristol is a 400 mile round trip over motorways, dual carriageways and a lot of A and B roads, and there you can feel a difference. Combined with the pedal box the car is a monster now. The difference from the FSR only really shows up at the medium-high end of the rev range and is more apparent the higher the gear you're in, which is probably why it doesn't really show up much in commuting conditions.
The car now pulls in 6th gear the way it used to in 4th before. Overtaking is really effortless, and in 3rd it now has enough torque that I've spun the wheels a few times (and that's with the grippy winter tyres on, not the crappy Bridgestones). Not sure what else there is to say - I won't be returning either unit. Combined together they've made the car a lot more fun to drive.
Insurance wise I did have some trouble and it would be worth researching this before you commit to a box. I was previously with VW for the first year (they were a bit pricey at a little over £500, but I liked the 'we'll use VW parts to fix your car' guarantee) and they declined to quote at all on the car with the box in it. NFU Mutual and Adrian Flux were quoting in the £1000-£1200 bracket, and LV would quote at around £700 but wanted me to also have a tracker in the car (with associated subscription cost). In the end I went with Elephant at around £330 - which is obviously a fair bit cheaper than last year's policy on the car without the box in it - but at the cost of using an insurer that it down at the bottom of all the customer satisfaction surveys. In 11 years of driving I've only had to deal with an insurer once about an incident, so I'm gambling on that remaining the case this year too - obviously you may not want to take that same risk.
