For tyres look around the forum. Quite a few people have changed the swift tyres. The ideal size is 195/60-15. It does not touch the inner wall.
Recommended tyres are michelin primacy or preceda. Those are the only ones available. If your lucky you may get the yoko AVS ES-100.
Mods to the intake and exhaust are not recommended on a turbocharged diesel car. Especially when the vehicle is new in the market.
Even Pete's tuning box will not be available for quite some time for the car.
Will this be your daily drive? With the 195 tyres expect the mileage to come down as the contact patch will increase by 30mm on each tyre.
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