Hi and welcome! There's a small number of things to be aware of for a 90000Km BK MPS 3 - the first one popping to mind is timing chain and VVT actuator. These had a weakness in BK 3 and GG 6 MPS models that requires the chain and VVT actuator to be replaced / upgraded as it begins to wear. That's commonly around 120-150,000K and becomes an urgent issue if you get the wear symptoms for a rattle noise at startup.
Regarding first mods, The #1 popping to mind is a rear engine mount, although you should check to see if it's already got one. I would recommend the CPE stage 2 rear engine mount myself.
Performance mods are plentiful, but often require tuning and dependencies such as an upgraded fuel pump. What to recommend depends on how far you are intending to take it. If you aren't upgrading the fuel pump I'd suggest safest option is to stay away from replacing the intake MAF housing or downpipe. I got good gains doing turbo inlet pipe, top mount intercooler and turbo manifold when I went down this route. Have a search around the forums, I'm sure you'll find plenty to pique your interest.
"Blue Meanie" 2007 Aurora Blue MPS 3 - 18x8.5+44 SSR GTX01 - 235/40R18 Michelin PS5 - 3.5" ETS TMIC - CPE stg 2 mount - HKS/CPE BPV - 2XS inlet - 2XS short shift - Corksport turbo manifold - HT 98 octane tune - Leather/Aluminium handbrake - Momo shifty knob - 7" touchscreen - JDM Mazda Retractable dashtop screen assembly - Bespoke Raspberry Pi Android based GPS/Carplay and instrumentation - 36AH reserve battery and C-TEK isolator - TEIN Street Advanced coilovers 1" drop - Superpro bushings - 220Kw/410Nm.
"Lipstick" 2013 Velocity Red MPS 3 - 18x7.5+48 Enkei RPF1 -225/40R18 Federal RS-RR - CPE TMIC - COBB inlet - CPE stg 2 mount - COBB Stage 1 98 octane tune - COBB shifty knob - 2XS short shift - 2XS turbo manifold.