Just be aware, most of the cats Magnaflow
sells are not high flow cats. Most of them are ordinary 400 cpi ceramic cats. This is high flow by 80's standards, but most stock systems use the same density, so the Magnaflow cats would have no advantage over stock in terms of flow.
If you do want real high flow cats, you need the Magnaflow Spun converters, like these
Be advised, these are overly priced for the low quality. They use a palladium only substrate that is known for its poor performance. They can be found cheaply because they do not have enough precious metals to be effective cats. You will likely end up replacing them every year. If you want good high flow cats, you need these.
These have a rhodium/palladium blend and the loadings are up to 4 times higher than those found in other brands, resulting in a durable long lasting and effective product that will last for many years.
Since you are a TW member, you qualify for a 25% discount on the cats.
On sound, the high flow cats would still sound pretty sweet, but it will clean up a lot of the rasp.
I am running real high flow cats on my van.