I recently bought a used 2007 Mazdaspeed 3. It had 41K miles and had some nice upgrades. All the work was done by Bell Engineering in San Antonio. The intercooler had been relocated in front of the radiator. They replaced the engine management chip. It has a cold air induction system and a hard motor mount. According to the previous owner the car dyno'd at 300HP at the front wheels. I installed some Kumho Ecsta ASX 225x40 tires on it when I bought it.
Shortly after I got it the intercooler mount vibrated against the AC condensor lines and broke one. I took it back to Mazda South and they replaced condenser at cost and reconfigured the mounts to isolate the intercooler farther away from the condensor and associated lines.
I love my MS3. It is bad ass. I have owned at least 15 Mazdas including two RX-7s, a 626GT, an MX-6GT, two Rotary Trucks, a 2002 Protege5, 2006 Tribute(wife's car) and numerous other Mazdas.
My only question is: the previous owner ran Amsoil and when I did the first oil change I used Mobil 1 synthetic. Should I change sooner than the recommended interval?
Mac