Boy has it been a busy 12 months...
I purchased these mods because I consider them to be the best available - each choice was made with no less than a full weeks worth of research in to competing products. I live in the UK though, so your mileage may vary as I don't have as much choice as you Americans
In chronological order:
Remus Ti2 Titanium Race Exhaust
Purchased from Design911.co.uk for ~£2000 (inc. VAT)
Fitment took approximately 3 hours @ £72p/h (look out for rusted bolts)
Impressions:
Love the noise, gave a seat of the pants improvement, looks fantastic! Probably my favourite mod!
OEM GT3 Throttle Body + IPD 'Competition' Plenum
Purchased from Design911.co.uk for ~£1000 (inc. VAT)
Fitment took approximately 4 hours @ £72p/h (fitment of the larger plenum is a real pain)
Impressions:
Seat of the pants improvement in torque, slight change in exhaust note.
Softronic ECU-Remap
Purchased from Design911.co.uk for ~£800 (inc. VAT)
DIY Fitment, very easy once the procedure was known but Design911 did not provide instructions and so was harder than it should have been.
Fitment took approximately 3 work days (from scanning the car to receiving the new file)
Impressions:
Solid remap, fixed an occasional CEL light brought on due to other modifications.
Fabspeed Sports Headers (200Cell)
Purchased from Evan@Fabspeed from this website (awesome guy) for ~£1500 (excl. VAT)
Fitment took approximately 3 hours @ £72p/h (fitment was easier due to fresh bolts from exhaust install)
Impressions:
Wow this sounds awesome, and definitely gives an improvement to power - this is easily my second favourite mod.
Evolution Motorsport V-Flow Intake (with synthmax filter)
Purchased from Regal Autosport(UK) for ~£700 (fitted inc. VAT)
Fitment took approximately 1 hour @ ~£72p/h
Impressions:
I like it, but can't explain why - perhaps I just get a kick out of modding my car, but either way I can now maintain the air-filter myself.
GT3 Master Brake Cylinder + SRF Castrol Brake Fluid
Purchased from JZM Porsche for ~£385 (excl. VAT)
Fitment took approximately 2 hours @ 72p/h
Impressions:
Great pedal feel, an absolute must have for any Cayman or Boxster owner wanting to track their car.
GT3 Front Brake Ducts
Purchased from Gert@Carnewal from this website for ~£20 (or some other figure - it was very cheap!)
DIY fitment took approximately 2 hours because I took my time and it was sunny out
Impressions:
Once again I like them, and i'm sure they make a difference to the brake temperatures on track, but i've never noticed (this is a good thing!)
Girodisc 340mm Front Discs + Titanium Shims + Pagid RS29 Brake Pads (Yellow)
Purchased from Design911.co.uk for approximately £1300 (excl. VAT)
Fitment by JZM Porsche took an unknown amount of time (left it with them all day whilst I went to work - watch out for air bubbles in your system, they will need to be bled once or twice)
Impressions:
Pads are rock solid and last forever, increased breaking torque provided by larger discs, improved cooling... great mod.
Mase Engineering ECU Tuning (custom dyno remap)
Purchased from Steve Mason@Mase Engineering for ~£400
Tuning process took ~2 hours
Impression:
This guy is hands down one of the best people i've ever had the chance to meet in the automotive tuning industry - Fantastic remap, fantastic job.
RSS Tarmac Series Lower Control Arms (Adjustable) + track alignment etc
Purchased from Center of Gravity for ~£1300 (incl. VAT)
Fitment will take approximately 6 hours from start to finish including pre/post inspection drives, alignment and consultation.
Impressions:
This is being done Thursday this week, i'm sure i'll voice my opinion somewhere on this website once i've had a track day to digest the changes
I think there are some other smaller mods, but they are currently escaping me... i'll add to this list as I remember.