update punching

In the 'old' days the cats were much more restrictive with pellets of rare metals and such in them. Almost all of the newer cats are of the 'Honeycomb' variety now. This newer setup is VERY non restrictive. They cost much less to produce as well. Thats probably why they are used across the board now anyway. Most mufflers would be more restrictive now. I doubt if you would see any performance gains from the removal of the cat let alone drilling a few holes in it. That is providing they are using this design of cat and it is adequately sized in the first place.

Picture of cats

[ This message was edited by: Stlakid on 2006-12-17 12:15 ]

On a car you do pick up HP by removing the cats. I know people who have seen 4-6 HP by just removing the cats. I use high flow cats on my car, can't justify the pollution.

umm pollution.well the belief that Catt's make a engine run cleaner is true to a point.they where developed to help the
pollution problem because of unturned engines that 90% of the masses run on. truth be told a well tuned non emission car will run as clean or cleaner than a emission car example i live in fld for 12 yrs. and they had vary tight emission laws an had to pass a sniff test yearly.i had a 85 olds 98 4 door diesel that was convert to a gas v8 carb witch was exempt. no cat but they still ran the sniff test and was shocked to find that it was cleaner than 98% of the cars they tested from 91-96 the tank got 27 mpg hwy at 70 mph.so if u keep a engine tune up it runs clean and yes they have improved a lot in the last 10 yrs less emission thanks to computers that reg.cks engine performance.but they are still limited to the program example run a colder thermostat say a 180% instead of a 195% an it will run rich pick up some power and loss mpg