Catalytic converter racing by-pass – Bischoff – Porsche 911 (993)

Two types of catalytic converters were fitted to the 993. The Bischoff, the most common, has oval inlet pipes and two inlet flanges at 45° to the converter. The Gillet has round inlet pipes and flanges at 90°. We offer every variant for both types.

The most radical option in our 993 catalytic range: this by-pass replaces the converter, improves flow and delivers a markedly sportier sound, with an 8 hp gain over a stock 993.

Regulations: this exhaust has no catalytic converter. French regulations require the converter to be retained: this version will not pass the French roadworthiness test (contrôle technique).

Fitting

• Original interfaces, direct replacement without any modification; adjustable flange for a stress-free fit
• Mounts under the car between the manifolds and the mufflers in the rear wings. Average fitting time: 2 hours including removal. Lift essential
• Before removal, unplug the Lambda sensor in the centre of the converter (easy access). It can rarely be reused: be ready to replace it
• The 3 bolts on each inlet flange are often seized: apply penetrating oil well in advance
• Tighten all nuts progressively; fitting kit included: gaskets, stainless bolts, stainless lock nuts, high-temperature copper grease