Exhaust or air induction on yaris diesel.

[Ziishan]

Hi everyone, new to this site and forum, only just bought a Toyota Yaris 1.4 D-4D. Its the 2010 model.

Wanting to spice it up a bit, already had windows tinted and wired a sub & amp plus tweeters on stock headunit (did it myself )

Anyhow im now looking at making it sound better. Been told a new back box would make no difference coz its diesel, and air induction kits will apparently make it slower and more fuel consumption.

Could anyone advise me on those two matters... Exhaust and/or air induction? Which is better and also a type that i could use?

Thanks in advance people.

P.S dont know if theres a difference but im a UK yaris owner