I think those two systems are very similar. slp will be a bit louder IMO. I am not a huge fan of the loudmouth sound but it is loud. if you are keeping you stock midepipe it will really not be that loud. both of these exhuasts are very loud with an o/r pipe so keep that in mind. I personally like the
borla and bassani in sound over both of those but it is all about personal taste as long as you like the sound
borla, bassani, mangnaflow/pack, slp all make a great exhaust. I would just listen to clips and buy the one you like the best.
As for the slp making fbody parts coments, what does that have to do with anything.
magnaflow,
flowmaster, bassani, mac, hooker, edlebrock,
borla, etc makes fbody exhaust as well. I don't understand you logic. any company that makes are part for a chevy can't be run on ford. that is the gayest thing I have ever heard. Comp, crane, trickflow, worldproducts, dart, lunati, crower, msd,
vortech, paxton, Ati, nos, edlebrock, I could go on all day make parts for both ford and chevy.