Hi All and thanks Ess5 for the excellent write-up. Looking forward to the picture diary and the before and after comparisons. I want to take some 'in-car' recordings as you guys just have to hear this! then I will try and find out a way to post them on here! Patience please!
FWIW, here's my write-up on the modifications...
The Milltek
1) Visuals: Looks fantastic, a small change to the car, with a big impact… it says to the eye ‘not just an ordinary S5’. In fact the more you look, the more you think… bloody hell that thing must have some lump under that bonnet (hood for those in the US!). Downside… not quite as ‘stealthy’ any more… but that’s not why we got the Milltek!
2) Sound: Awsome! (sound files coming soon) The sound does this engine justice… The Milltek is quite a lot louder when you use the throttle, but civilised when driven gently. The sound in the cabin is amazing! …just right… any louder and it would be too much (I will try to take some in-car recordings later too, but have no ‘before’ recording of this). The best thing is the tone… the Milltek is far more sonorous, making the V8 sound just amazing at higher revs, whereas the stock exhaust disappoints when revved… to the point where I used to feel bad and change down early to ‘look after the engine’… but now I just want to hear it rev… and rev… Application of the power when exiting a bend, now not only shoves you in the back, but makes all the right noises too. The fun-factor just went up 200% !!

Thus the car is transformed from a ‘beefy V8’ with the stock exhaust to the sound of a ‘supercar’ with the milltek… no joking people turn to look for the car as soon as they hear this car and blokes just grin as you burble by…. Any down side? Perhaps… at low revs (less than 1,500rpm) a lot of throttle input tends to be a bit ‘boomy’ so you feel you want to change down to accelerate, rather than labour the car in-gear.
3) Performance: I have yet to confirm this with Ess5, but there’s noticeably more mid-range torque. The power seems to build faster and pulls like a train, to the point where the steering starts to feel slightly light. The car is definitely more responsive and feels like it wants to rev more, making it more ‘sporty’ to drive and improving the ‘fun-factor’ too. Any down side? I think that the low-end torque (<1,500rpm) has dropped a little (as would be expected… see my egg-head notes in the ‘pictures of S5 Exhaust thread! Hey Ess5!

). Although this may be a function of the boominess making this seem more laboured. Although TBH at these revs this is not an issue unless you have your mother-in-law-to-be in the passenger seat and need to drive around at 30mph in 6th gear all day!
1” Lowering and 15mm Spacers:
1) Visuals: Well, The car is transformed. It already looked fantastic… that’s why we all fell in love with it. But honestly, look at the pictures… it looks even better in the flesh where you get a proper sense of scale and proportion. The rear quarter is ‘perfect’ the wheel/tyre sits perfectly in the arch and right to the outside of the vehicle. Most importantly, ‘it looks right’. The front wheel does look like it has spacers, due to the way the bumper and front valance meets the wheel, but we conducted a test with and without and all preferred ‘with’… although perhaps I will experiment with just 10mm at some point… Again though, most importantly, the stance and width matches the ‘perfect’ rear so the car looks just right… testimony to this is the fact that Domestic Ops didn’t notice I’d changed the car… meaning it has made a big change in the looks, but doesn’t look out of place. All the guys, however have gone ‘wow’! it’s so much better and can’t believe it’s only 25mm down it looks that low and planted.
2) Ride: It is definitely a firmer ride, and about as firm as you would want to go for a car you use most days, but I have not hit any bumps yet where I’ve thought it was too firm… and I have been ragging it down country lanes with grass growing down the middle and pottering through town with road works and exposed ironwork etc. From the fun-factor side, this car now feels like it is travelling at the speed it really is, adding more grins per mile! There is no doubt, that the stock suspension is smoother and fractionally quieter and this serene refinement has been compromised slightly so the mother-in-law to be might not be impressed… but it’s not her car!
3) Handling: This doesn’t disappoint. Grip levels are still the same… as you would expect, but the car is definitely more ‘alive’ and responsive… with less dip, dive and body roll, more of the steering input seems to go into a change of direction and less into a change of balance… although the stock is pretty good to start with. Balance wise, the high speed lane-change manoeuvre is completed with much more control and poise and the added steering weight provides a little more feedback, adding to the confidence in situations such as this, or adverse camber and wet road driving. Any drawbacks? Perhaps… the steering feeling a little light when accelerating flat-out, but it’s hard to tell if this isn’t actually just having a little more ‘feeling’ through the wheel (or the Milltek giving more grunt) as opposed to any change in grip levels at the front.
Insurance damage: £29 increase to the premium… not exactly re-mortgage territory.
Fuel damage: The engine now tempts you at every moment to “Try me! Go on! You know you want to; rev me please, give it to me, satisfy yourself!!” The result is that I now have a much heavier right foot and the fuel costs associated with it… but hell, I’m addicted! My kids can go without meat to pay for it!
Summary of both of these Mods…
“Perfect” I am delighted with the transformation and this has ‘finished’ the car for me. I really can’t see anything else I would want from a car. I have to admit I was apprehensive, taking a ‘near perfect’ car and changing it slightly to suit my tastes in looks handling and noise (which is why I bought the stock) but have no regrets at this point and I’m glad I did it right now. Money very well spent.
Finally…
I cannot praise APS enough. They were consummate professionals, knowledgeable, friendly and very accommodating. They now have more experience with modifying A or S5s than any other UK outfit and have by far the keenest prices… it is worth the fuel to travel to these guys both for the money you will save and the confidence that they know what they are doing and look after your car like it was their own. I now understand why they have the awards that they do. First class.