The GT exhaust is a reworked original exhaust, modified in our workshop. It looks just like stock on the outside but the internals are changed to a better breathing, less restrictive exhaust. The result is a louder and deeper sound with no reasonance. On the cars with Tip gearbox, there is no droning nor resonance between 2200 and 3000rpm. This exhaust does not trigger check engine lights and is not giving problems with emission checks during the yearly technical inspections like MOT, APK. The modified exhaust looks 100% original on the outside. The installation of the GT exhaust does not cause "Check Engine Lights" nor gives you problems with emission checks. There is an increase of +5 to 7HP.