I was so annoyed when I first drive my new SP23 (GT) as it was so noisy on the highway and the suspension seem to make a lot of noise. I had it checked at the first service and was told that ALL Mazda3s were noisy. Not mine anymore. I changed the tyres (tires).. I put 18"x7" TSW wheels with 225/40x18 Sumitomo HRTZII..the difference is remarkabale. No noise, smoother ride (despite the ultra low profile), and greater handling prowess. The car has been tranformed it is beautiful to drive...so much for much more expensive Bridgestone standard fare. RED SP23