I realise that for most of you this is going to be preaching to the choir, but after running the Tuning Developments NA package for 6 weeks or so and getting a few road miles and a track day under my belt, I thought I'd share my experiences for anyone that's considering having their car upgraded.
I had the install completed just before Christmas; I stayed in Runcorn at a very cheap hotel, and made my way over to Warrington at 9am. The work took until about 2pm to complete, including TD's own catback and the MTEC shift springs/Powerflex gearbox insert combination. I spent some time talking to @Mike@TD.co.uk whilst the work was being done and it's clear that he knows his stuff with GT86s. He kept me updated with how the work was going, and also kindly took me for a passenger ride in the turbo GT86
After a couple of post-install dyno runs and a road test, I took the keys back and prepared for the long journey down the M6/M5. Just pulling out of the estate where TD are based it was obvious that the engine revved more freely. Spending a bit more time with the package since then has only reinforced that initial impression. Even keeping the revs below the old torque dip the engine response feels more immediate. The real benefits become obvious once you get over 3500rpm though. Plant your right foot at 30mph in 3rd gear, as you might do on a sliproad, and the car pulls effortlessly all the way to the national limit. Whilst you'll see a ~10% gain in peak power over a standard car, the real improvements come at 4000rpm where you have 25% more torque, and the torque level is almost constant from 3000 - 6750rpm, rather than 4750 - 6750. It practically doubles the width of the power band, and as you'd imagine the result is like driving a different car. You can keep the engine in its sweet spot without running it to the redline in every gear
An added bonus of the flexibility is that it allows you even more potential to exploit the chassis balance and adjustability on the road. The extra torque means that you have more options coming out of a corner. I was always a fan of the way that you can neutralise understeer with the right amount of throttle input, and the flat torque curve and sharper throttle response really helps that characteristic shine.
On track the gains are less obvious but still there. At track speeds you would normally have been above the dip anyway, but at Donington a couple of weeks back we had quite a wet morning. I didn't know the circuit, and combined with the rain (and the need to drive home afterwards!) I was fairly cautious early on. As well as taking less corner speed, I was shifting at lower revs. The ability to upshift early without dropping into the dip meant that I didn't feel I was losing too much by doing that. I'm looking forward to getting back to Castle Combe at some point too. Last time out I was short-shifting to 5th before Folly to avoid an upshift through the corner, and the improved torque curve should mean that it's not so costly to do that.
As I mentioned after the installation, I also found that fitting the NA package didn't increase my insurance premium, which is through one of the brokers in the Insurance section.
As for the other changes to the car, the catback has given the exhaust note a nice throaty bass in day-to-day driving. It was initially a little harsher and had a slight drone at motorway speeds, but has mellowed nicely over time and is now quite tuneful. I can happily listen to music at a sensible volume, without the exhaust drowning it out. On track it really sings with a lovely race car note.
The MTEC springs and Powerflex gearbox insert have made a surprisingly big difference for such an affordable modification. Cold-start 2nd gear issues aside, I'd always thought the GT86 has a very good shift from the factory. That the springs and insert have improved on it so noticeably is seriously impressive. It has a really positive feel, and the weight and precision are nothing short of exceptional.
I wouldn't hesitate to recommend both Tuning Developments and the NA package. The install looks great quality, Mike and Nick know their stuff, and it really is excellent value.