Title says it all. thanks for everyone's help; I'm learning a ton here!

 

This is an exhaust system that replaces everything downstream of the catalytic converter. By leaving the "cat" alone, this generally will not affect factory warantees. On the S2000, such products produce minimal HP gains since the stock system is so good. Aftermarket systems are for customizing the "sound" of the car. Some systems may, in fact, result in HP loss.

 

I should probably know this, but what does the catalytic converter do?

 

It is an emission control device. It's filled with a sort of honeycomb/criss-cross sandwich material impregnated with a "catalyst" (platinum I think). The bad products of combustion such as carbon monoxide, sulferous compounds, etc, are "converted" to less environmentally harmful gases like carbon dioxide and other less harmful sulfer compounds. In some cars, this is the most limiting factor to performance in the exhaust system. That's why some people remove the "cat" for that extra punch. On our car, this is not a good thing to do since there is an oxygen sensor inserted in the cat. Putting in a straight pipe would cause the computer to see a fault. Putting in a high flow cat is a waste money since the stock one is already a high flow cat. Honda knew there stuff on this one.

 

A catalyst by definition is a device that promotes a chemical reaction without being consumed or altered by the chemical process.

Two components of automotive combustion assist in the formation of photochemical smog...nitrogen oxides and unburned hydrocarbons of various types.The catalytic convertor performs two distinct functionsbut the catalyst is the same (a metal oxide or noble metal):

1) Oxydation of CO and unburned hydrocarbons to carbon dioxide (CO2) and water (H20)
2) Reduction of nitrogen oxides (NO) to nitrogen gas

Both conversion are supported by "platnum", a noble metal, which can be matrixed with Al2O3. The reaction here weakens the O2 bond and makes "O" available to the CO for reaction.....Co2 is formed. Likewise NO is broken down to N2 and O2 but the reaction here is very slow....platnum speeds this reaction also. The sulpher XViper is referring to is actually something somewhat new. SO2 which is used as a fuel additive may likewise be oxidized into SO3. This is a problem as S03 dissolves in water readilly (i.e. rain) to form sulphuric acid.......ever heard of "acid rain"? This can lead to health problems in high traffic areas.

Lastly catalysts will break down over time..either due to mechanical failure of the matrix, due to heating and cooling cycles. Or poisoning of the catalyst, usually due to fuel additives (i.e. lead). Leaded fuels produce tetramethyl lead....a strong poison which is why leaded fuels where done away with in 1975.

Utah