I want to mod my 2013 Mini Cooper S paceman all4 but don't know what to start with.

 

Manual or auto?

If a manual, I would recommend:
- torque arm insert
- clutch pedal bump stop
- short shifter
- weighted shift ****
For either, I'd recommend a JB+.

Those were favorite mods on my R60.

 

automatic transmission

 

Oops I edited while you were replying. JB+ is good bang for your buck. I liked having a front strut bar, but I never got around to a rear sway bar.

 

Dw, Great Thank You! i'll look into that.

 

non-runflats - best mod for any BMW and Mini (except M and GP since they come with non-runflast from factory).

JB+ is poor advice. Add power to an engine that suffers from issues in stock fashion anyway? I'd leave it alone!

 

Front strut brace & rear sway bar is a good start. Then add an Ultragauge.

 

I have a 2013 Paceman JCW, 2013 Cooper S and an 04 Mini Cooper S and a 500 whp 05 WRX STi.

Best modification mods to me on my JCW Paceman are rear Swaybar, Front Strut bar (this gives better turn-in and keeps the car from having less roll. I would like to lower it but its my daily. I also have the NM Enginer Power module. It think its much more responsive than the JB+ ECU which I've also had. The NM gives quicker response through the power band and less laggy. Also the Throttle Booster for the gas pedal, that's really a fun mod. I keep mine on the least sensativity.
Maintenance is key with these cars. Replace all fluids to new and keep the oil clean ( I use Amsoil ). These car are not happy when there tuned with out Tru DYNO tuned with power mods. Do not slap on intakes and exhaust mods with out proper tuning.

 

Rear sway bar, lighter wheels, and non run-flat tires gave me the biggest bang for the buck.