Quote:
Originally Posted by
66cat389
I know I will probably catch some flack from some of our more environmentally conscience members here, but I have to ask...
Has anyone here gutted their cat or just replaced it with a straight pipe? I am wondering what the consequences of doing something like this would be?
Other than the obvious emissions test failure.....
I've had a good deal of experience with this. Before I start though, I DO consider myself an environmentalist. I won't bore you with everything I do, but I do also consider myself Republican, so with that perspective, take what I say with the understanding that I don't want to give any bias.
A car's engine is designed to perform at certain RPMs. Most engines can only perform well in the low to mid-range power, or the mid-range to upper rpm power. This is why VVT is so great because it takes advantage of the entire range! However, taking that into consideration, the whole package must be designed to make the car perform with an acceptable performance range (with no major bias). At the same time, they need to contend with a number of restrictions (like CAFE, etc...).
When they designed the stock catalytic converter (along with the stock piping) they did so, so as to optimize performance while meeting emissions, sound, and cost restrictions.
Replacing the cat with a straight pipe WILL give you significantly more power in the upper rpms, but it WILL affect to some extent the lower rpm power range.
An IDEAL solution to this is to get a higher flowing cat. The Clear Image one is nice as it's nearly 200cfm more flow than the stock catalytic converter. This gives you something in the range of 95% of the optimal performance you'd see in the top-end, but with no loss whatosever to power in the bottom end. This makes your car ultimately a faster vehicle in every respect, and makes it a more well rounded modification for the street.
Going with a straight pipe will be ideal if you plan on racing the car full time (where you'll spend 90% of your time in the upper rpms). But for a daily driven car, put a high-flow cat on.
Emissions will be relatively the same in day to day driving with a higher flowing cat, but when you really get on it, you'll be putting out significantly more emissions in the upper rpms than you would with a stock cat. However, you should still pass standard emissions tests (if your state has those) where they ask you to keep it at 2,000 rpms for a couple of minutes.