As with all of Milltek’s systems, this latest Subaru system is hand-finished in their UK factory, from the finest stainless steel. Precision CNC mandrel bending offers flowing, uniform-diameter bends that maximise gas-flow for impressive performance gains. Best of all, whichever system option is chosen, the Milltek exhaust endows the latest STI with a sonorous flat-four burble that really brings the character of the EJ25 powerplant to life.
After careful dyno testing, a 76mm (3”) tube was specified to give the greatest balance between back-pressure, flow and acoustic performance. The result is a system that offers a deep, rumbling tone when required, or civilised, refined cruising when not.
Many system options are available, including a fully de-catted large-bore downpipe, as well as a high-flow sports cat option. Those preferring to fit a cat-back system can opt for either non-resonated for a few extra decibels of that glorious noise, or for those wishing to stay fully legal in all countries, there is a fully EC-approved resonated cat-back system which comes with full EC-approval.
Quality and acoustic improvement are a given then, but the Milltek system also promises impressive power gains. During independent dyno testing, the half -system elicited gains of 15bhp, whilst the full system was able to achieve more than double that. On cars fitted with aftermarket software upgrades, gains of significantly higher outputs were achievable, thanks to the free-flowing nature of the pipework.
This latest design uses proven technology and design from Milltek’s system for the previous ’08-on STI, combined with bespoke components to get factory levels of fit. The exhaust terminates in two stainless steel boxes, complete with a choice of aesthetically appropriate trims. Choose from the tasteful GT100 trims in either polished stainless or titanium finish.