The STaSIS Signature S4 is available in Touring and the Challenge editions, both featuring an engine kit that boosts the 3.0-liter supercharged V6′s output from 333 bhp and 344 lb-ft of torque to 410 bhp and 370 lb-ft.

The base Touring Edition package also includes suspension, brake and exhaust system upgrades as well as 19 or 20 inch alloy wheels, while the Challenge Edition comes with larger 6-piston brake callipers and lightweight forged aluminum wheels.
The STaSIS Signature S4 packages are from APS of Brackley, starting at £12,500 including VAT (20%) and installation.
STaSIS Signature S4 Components

Signature S4 Touring Edition
• Exhaust – Quad outlet with low RPM resonators
• Engine Tuning Software – performance increases to 410 bhp / 370 lb.ft
• Suspension – 1“ lower, increased spring rate, anti-roll bar kit and matched bushings & bump stops
• Brakes – optional high-performance street pads and braided stainless steel lines
• Wheels – 20 inch x 8.5 inch lightweight cast aluminum wheels, Optional 19 inch x 9 inch lightweight cast aluminum wheels
• Tyres – high performance

Signature S4 Challenge Edition
• Exhaust – quad outlet with high RPM resonators (recommended for manual transmission)
• Engine – tuning software – performance increases to 410 bhp / 370 lb.ft
• Suspension – Ohlins SL dampers, increased spring rate and high performance anti-roll bar kit
• Brakes – 6-piston Alcon monobloc calipers, 370 mm 2-piece discs (390-mm optional), stainless steel brake lines & high-performance pads
• Differential – high-bias centre differential (manual transmission only)
• Wheels – 20 inch x 9.5 inch ultra-lightweight forged aluminum wheels
• Tyres – extreme performance