Is a tj vrx cat the same as.standand tj. and what Hifow cat is the best 100cp or 200cp

Cats are the same between vrx and executive

With cats, 100cpi will be a better flowing unit.

The CPI stands for "Cells Per Inch" so, the higher the number, the more restrictive they are. Most standard cars come with 300-500cpi cats because of emissions.

If you do decide to change your cats, remember that you will probably fail any emissions test you do.

In most states 200cpi is legal but 100cpi is illegal. It's not really the cpi, it's the emissions test. 100cpi doesn't quite get rid of enough of the nasty things like nitrogen oxide or nitrogen dioxide (NOx), 200cpi usually does. No cop is going to demand to cut your cat open to measure the cpi, but they might decide to give you an emissions test.

Bottom line - a 100cpi cat will give you a very slightly freer flowing exhaust over a 200cpi cat, and you could be defected for it, but the chances of that are pretty damn small.

As they say in the classics, "you pays your money and you takes your chances".

Agreed,

Although it does vary from brand to brand. Unless you have clearance issues, best to just stick to the standard one.

Noobish question, but does changing the cat set off any CEL's?

No, the O2 sensor is before the cat on 3rd Gens, not sure on the 380
Plus there are a few here who have changed cats and haven't reported any CEL problems.