S4rt = same as s4r but with testasretta engine (weaponised 130rwhp) 10 spoke wheels from 848 (s4rs has lightweight wheels) same front & rear suspension as s4r (ohlins on s4rs) different paint & dash, I had the s4rt (Darren69 has it now) and the standard s4r suspension is fully adjustable and very good.
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