1. Clutch options.. The turbo clutch kits you see out there are fairly good. You more than likely have the stock disc that has the little springs on it (always fail). So the easy solution.......sachs kit. Replace pressure plate, disc, throw out bearing, pilot bearing, needle bearings. Check flywheel and you are done.
IF you want some thing a little more serious. I use a KEP plate, cup disc and fidanza flywheel. It works well but it gives the leg a work out.
2. Authority has been around for a long time. They do work. I suggest you search and read about chip options. It is a steady slope once you start modifying. You have to be very sure of what you want in the end..... A stock k26 will easill give you 230-240 rwhp.... If that is enough....... chips/banjo bolts are easy solutions. The only chip I would spend the money on at this point would be one from
www.vitesseracing.com
3. MAFs are available from vitesse as well.
4. Jason at Paragon is a great resource for suspensions.
http://www.*****************.com/ You will also find great info in the tech sections at that site.
At 110K the waterpump is probably due if it has not been changed. Normally it is swapped out when rollers and belts are done.
1.5 bar........well the stock guage can be hard to read unfortunately.... Normally your car will build to approximately.... ~1.75bar and bleed out to 1.5 at redline...
Now realize that .75 bar is the actual boost.... 1 is ambient. So you are generating ~11 psi ~3K rpm and down to .5 bar (8 psi) at redline...
A chip/boost enhancer will have you building 15 psi at ~3K and hopefully it would hold to redline. (but number of factors that can affect this).
Have fun...........and READ READ READ before you change anything.