This 2bular catalyser is to the highest spec - Euro 5/6 - a 121mm diameter 200cell HJS HD (High Durability) directional catalyser for all the 4-cylinder 2bular supercharged exhausts. Take a closer look at the middle pic and you can see the pressure lines where the casing has been crimped to hold the internal substrate securely even in the event of the hi-temp brazing being melted by over-heating caused by over-fuelling (a common fault on all Lotus supercharged motors).
The HJS catalysers use an 'S'-wound metallic substrate which is strong enough to take this crimp. Spiral-wound substrates would collapse. 121mm diameter is big enough to handle the power and with the famous HJS quality, good enough to pass emissions tests easily, year after year. Quieter than the 100cell designs too - something that's becoming even more important these days.
The gasket cup is TIG-welded to the flange. A unique 2bular feature. I guess some people don't have the skills or can't be bothered to do this. It allows the springs the same working length as standard and ensures a strong, gas-tight connection.
The conical reducer brings the pipe diameter to the correct 63.5mm diameter - any larger and you're losing gas-speed/performance. I've seen a 70mm diameter pipe used because it's easier to form the gasket cup on the end of that size and heh - just leave the flange loose(!) - lazy - and on the SC'd cars, you're losing boost/power. Recently been sent an aftermarket 2ZZ catalyser with a 3" diameter pipe - didn't even pass its first UK MoT! More catalyser info here -
The 2bular catalyser bolts to the factory manifold and finishes at the same position as the factory cat pipe, so will fit to any after-market exhaust or the factory item.
The revised pipework layout into the silencer keeps it well clear of the clam.
I SUPPLY A REPLACEMENT DOUGHNUT GASKET WITH THIS CATALYSER.
PLEASE NOTE I DO NOT SUPPLY THE 1ST LAMBDA SENSOR ANY MORE - TOO MANY BOSCH FAILURES.
EXPORT PRICE (No VAT charge): 996.00GBP
LEAD TIME FOR ORDER - 1 week.