Catalytic Converter
There's no point just replacing the stock CATS. You need to do the rest of the exhaust also. Assuming you're not in CA then what you want is a nice catback, and aftermarket 3" Y pipe and some LT's.
Custom dual setups are an option but space is limited on the Fbody and they can be a pain if you plan on an aftermarket torque arm.
Personally I really like the Pacesetter headers (coated) they are well made and pretty cheap, TSP (Texas Speed & Performance ---> a sponsor) offer them as a package deal with their own 3" catted Y pipe. These use Magnaflow Carsound cats, these are very good cats and will be fine on a 400rwhp setup.
The best cats are metal matrix ones, Random Technology offer them (7000 Series) and Magnaflow will be also soon. they are pricey but would be the best bet if you plan on 500rwhp+ using FI (forced induction).
Jet Hot & Hooker also make nice cheap headers and a catted Y is availble but I don't know which CATS are used.
QTP, Kooks & Stainless Works also offer nice high end stainless steel headers. Catted Y pipes are also availble for them.
Trending Topics
The Best V8 Stories One Small Block at Time
IMO get a catback first, as it will certainly add to the grin factor and you may gain a couple of ponies. I have the SLP LM and personally I really like it, very LOUD and deep with no rasp at all (don't believe some of the other people, lol).
But be warned if your car is a DD (daily driver) then it may be a tad too much for some. The SLP unit is built very well and fitted as good as the factory item does. If you do upgrade to LT's and a new Y pipe make sure it is a catted Y you get, as the LM is reknown for becoming far too loud and raspy with an ORY.






