With the stage 2 things get a bit special. Firstly the exhaust ports are CNC milled out to achieve perfect port size, shape and position. We are unique in using true 3D cutter paths, cad-cam generated. Long series ball nose cutters machine the ports achieving true 3D transition from port face to throat. Only GTT do this! No manual method can achieve this level of accuracy, nor maintain consistent metal removal this far down the ports.
Secondly the exhaust valve seats are increased in diameter by 2mm internally, giving big improvements in getting the exhaust gasses out. On top of this there is still around 25 hours of manual fettling and polishing carried out on the inlet and exhaust ports, throats and combustion chambers. We also flow the manifolds and even the exhaust header pipes if required.
Power figures of up to 290bhp reported by customers (M45 supercharged) or 393bhp (GTT turbo conversion).
Fits: all Gen 1 petrol models.
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