High Flow Cat

For a long time I have been running the 80mm cat back back exhaust with the 3 inch CES dump dump but with the original compliance fitted small catalytic converter. Finally I purchased a new catco 3 inch high flow item, so that I would finally have a complete 3 inch exhaust.

Comparing the new to old items shows the difference in size to be very great. The old item had some dodgy welding that had created a choking neck even smaller than the flange, maybe around 2 inches in diameter. Therefore this would have created a bottleneck in the system that would perhaps explain the minimal top end gain made when the CES dump was fitted.

 cat1  cat2

For once I had no hassles fitting the cat, except that only three of the four old bolts and nuts were still under the car. I found a suitable replacement in my box of spares. I must tell of the importance of wheel ramps or similar when doing a job like this. Working under only a jack is extremely dangerous and the force required to loosen and tighten the nuts could easily shake the car off the jack. You should find like most exhaust bolts that they are 14 mm heads.

With the new cat in place the system now looked complete, with consistent fat piping running the length of the car.

cat3

On the Road

Road testing seemed immediately positive, with some more mid range urge and slightly quicker boosting. Wet weather however, severely limited the safe testing that could take place, so a further testing had to be delayed.

In the dry there is a noticeable gain when the turbo first begins to spool, giving a smoother and stronger ramp onto boost. The exhaust note also seems slightly deeper too, but not any louder overall, which is nice. The increased smoothness in power delivery also helps traction to some extent, so in a straight line is noticeably faster.