I have an '05 R53 that I have owned for 95k "gentle" miles and it finally gave up the ghost. I need a new clutch and am a bit torn... I am not sure I want to drop a bunch of money (but can be swayed) and am considering:
- stock clutch replacement only (might sell car after/before?)
- stock clutch replacement with bottom/top end rebuild (may also put a higher boost supercharger)
- low probability: full engine swap with a Way or Sneed set of kit or build-out helped by a friend who literally designed and built race engines for a number of years.

Current mods:
Willwood big brake kit front
Oversized rear rotor kit
Stiffer sway bar front and rear
Megan coilovers
Cold air intake
17% pulley (I think... its been like 9 years since I put it on)
New suspension bushings

Limitations: I live in California and don't want to make my car un-smoggable... I am open to swapping out exhaust system every two years but what does custom ECU flash do to the car for CARB smog testing?

I have done a blow-down test and don't have the numbers any more but it was pretty good on 1 and 4 with 2 leaking ~40% and 3 leaking 25%. (if memory serves)

My rebuild thoughts spring from an engine removal clutch replacement - what components should I swap out other than the clutch if i do this? I did a supercharger oil change about 7k miles ago with thermostat and water pump replacement.

 

If you have the engine out, I'd plan on swapping out most of the oil seals/gaskets/o-rings, as well as the inner ball joints, front sway bar bushings, steering rack bushing, and lower control arm bushings if you haven't done them yet. outer ball joints and tie rod ends might also be worth considering, but they're not too hard to get to while the engine is in.

I think most tunes can be CARB compliant, as long as you don't remove your catalytic converter.

 

Passing smog check ... and being truly 'Carb Compliant' are not the same thing.

Modify the ECU... and you are no longer compliant... Many people will "pass" though... and I've even seen some without cats or fake cats pass.... But remember... these cars are not getting a 'sniffer' test... and would not pass, more likely than not, if a dyno or sniffer smog session were mandated.





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In the same place with my 'new-to-me' '05 R53. I plan on doing a Valeo single-mass flywheel conversion (TO bearing failed), ball joints, cross-over-heater pipes (rusted pretty bad), brake pads and rotors. More to be done... interested in what others chime in on with.
C