some S3 questions

[doubleseven]

hi there everyone
i am a beginner S3 driver who has used 1.8TQ A4 for a long time.
i want to know your thoughts about the following issues.

first of all, http://www.amtuning.com.au/enhanced_dis.html
what do you think about this system. I use vdo boost and egt gauge. and will this system show my egt since I have the pyro?

my car has supersprint middle pipe and rear muffler. it is also re-mapped by MTM. I am planning to put a carbon airbox from BMC. Has anyone tried? suggestions?

I use a forge diverter valve, may it have any problems with 1.6 bar peak boost since I am using its original silver spring? do you advice anouther DV?

when I go full throttle for a minute at 6th gear, EGT raises up to 1650F which is end of the gauge, MTM said 1650 - 1750 is okay at exhaust manifold.

my car seems to run lean, what may cause this problem. (we have checked it out with AFR, put the sensor at tailpipes.)

do you have any suggestions for audi S3, or my car espacially?

thank you