Google will be your best friend. I copied this off the autocar website :
Then from Wikipedia :
You can identify a TTS by its prominent, body-coloured front spoiler lip, a metallic grey-finished grille and rear diffuser, Audi’s trademark LED running lights, deeper sills, aluminium capped door mirrors, 18in alloys and a quartet of exhaust pipes from the outside – inside, it gets alcantara/leather seats, more aluminium finishing and grey-faced instruments.
On the mechanical front, magnetic variable rate dampers, with two settings, are standard, and packaged with stiffer springs and anti-roll bars. Otherwise, the TTS is largely stock TT, which means a lightweight bodyshell of aluminium and steel, the steel concentrated at the rear end in the quest for more favourable weight distribution
Then from Wikipedia :
TTS
At the 2008 North American International Auto Show (NAIAS) in Detroit, Audi released the first Audi "S" model of the TT range – the Audi TTS quattro,[23] with a heavily revised 2.0 TFSI engine.[23] The cylinder block, cylinder head and the fuel injectors have all been modified from the base 2.0 TFSI engine (ID: CDL). Together with other modifications, this engine produces a DIN-rated motive power output of 200 kilowatts (272 PS; 268 bhp),[23] and generates a torque turning force of 350 newton metres (258 lbf·ft) from 2,500 to 5,000 rpm.[23][24]
Under the hood of a TTS Roadster with the TFSI engine
It is available with a choice of either a six-speed close-ratio manual transmission,[23] or a six-speed 'S tronic' transmission.[23] In the United States, the S tronic gearbox will be the only available transmission. Like all Audi "S" models, it is only available with quattro four-wheel drive as standard.
The suspension is lowered by 10 millimetres (0.4 in) over the standard models, and includes "Audi Magnetic Ride" as standard[23][25] and a new two-stage sports-biased Electronic Stability Programme (ESP).[26] Radially ventilated front disc brakes are clamped by a single-piston gloss black caliper emblazened with a bold TTS logo, and a lap timer is prominent in the centre of the instrument cluster.[27] 9Jx18" '5-parallel-spoke' design alloy roadwheels are standard,[23] with 245/40 ZR18 high-performance tyres. 19" '5-spoke star' wheels and tyres are optional.[23][28] The exterior has some changes over the standard model – with a TTS body styling: with redesigned front, with larger air intakes, redesigned rear bumper, side sill extensions, and four exhaust tailpipes.[23]
Official performance figures for the sprint from standstill to 100 kilometres per hour (62.1 mph) for the TTS Coupé can be reached in 5.4 seconds, with the Roadster two-tenths slower at 5.6 seconds.[23] Top speed is electronically limited to 250 kilometres per hour (155 mph).[23]
Audi UK offered eight TTS cars for official use by the race organisers at the 2008 Isle of Man TT motorcycle races.[8][29]
The car went on sale in the USA at November 2008.[30]
In 2014, at the International Motor Show in Geneva, Audi unveiled the new TTS model for the 2016 model year, alongside the standard 2016 Audi TT model. Both models are planned to go on sale in the beginning of 2015.[31]