A very technically competent member of Cranmog recently fitted one of these - the end result was very good and looks fantastic - however beware !
The drilling of the holes into the floor to fit it is a delicate process . The fuel tank is a few MM the other side of the hole - so when drilling he drilled into the floor he stopped just short of breaking through and then punched through the last few microns with a drill bit - all was well although only a few MM between the floor and the tank - BEWARE ! You could end up swimming in fuel if not careful
There are others, all of which will be found by using the Search function and the word diffuser, but I believe these are two of the most comprehensive.
Thanks. First thing I need to find if the part is still available, but given the above I may not bother. I've got used to the rear end and (for obvious reasons) don't see it myself too much anyhow!
The S1 rear is significantly narrower I recall so modifying one is unlikely to work. It would be possible to create a bespoke one of course for the right investment.
Converting the s1 to side exits is non trivial as the sills are thinner (it was of course managed on the GTN) though you may run into issues with sharper turns on a narrow bore pipe restricting the exhaust. Factory used to supply parts, but the s1 conversion was well over 2 k plus vat plus fitting. The s2 etc were less than half the cost. These parts are probably also no longer available (they weren't exactly in demand at the time) so it may be the case of going to a specialist exhaust manufacturer - at which point with an S1 you are doing a non factory mod which may restrict your ability to sell when you want to move the car on.
On the diffuser, remember that its purely cosmetic, adds weight and drag and provides no performance benefit. Looks cool though. I had one on my s2 and s4...
Got mine fitted on my S3 for £352.73 from Richard Thorne. They originally said it would take an hour but after wondering around for 2 hrs then a pub lunch using their courtesy car and another 1 hour looking at some great Morgans again it was finished. Its not easy to retrofit but worth it. Good luck
