As was mentioned, the generic high flow units have a risk of failing emissions, and some have a risk of setting a catalyst code. It can go either way. Some 3800'* have been able to pass emissions with no cat, others can't pass emissions to save their life.

It may be worth trying a standard aftermarket or high flow unit, especially if you plan to keep maintenance in top shape. If you are concerned about a more definitive solution, look to the units using the term 'Heavy Metal', as those usually solve the problem if the generic units aren't enough. I don't feel that stock replacement is necessary.

On another note, not sure if its really worth his effort down the road. A few years ago, I paid $1100 to replace the entire exhaust on my Bonneville. So, $1400 might be a better path for him to take instead of trying to get a car to pass emissions in the future, or some other issue that may arise with the installation of an aftermarket cat. Plus, it will more than likely have a good warranty.

yeah, I understand what you're saying. I'll have to give it some more thought. Thanks for all your help both of you!

How in in the world is that possible for Nox/HC gasses? It would almost have to be perfect combustion in the cylinders, which is impossible....

I have always cut the cat out at the welds, and replaced with GM cats.....hard to believe they are not still available....

I will agree, there haven been other 3800'* here that have had non-oem cats installed that did trip a code. I believe it was most of the 2000+ software systems. So, its gotta be in the programming.

I used this on both of my cars and have not had a P0420 code since installation. My 2001 Buick LeSabre has a gutted cat and my 1997 Olds 88 just has a straight pipe welded in place of the cat.
O2 Simulator, Angled O2 Simulator clears p0420 / p0430 check engine light simulator Angled Big Daddies Garage

Mad,

I am not talking about a code, I am talking about passing emissions without a cat...it won't pass......

Mad, is this piece easy to install? It looks like a great buy...

If you have ever replace an Oxygen sensor then you can do it.