I have AP Exhaust Xlerator series mufflers. The 18" (#XS1259) I had by itself with an otherwise fully stock exhaust (manifolds, cats, etc.) was perfect. It's a clone of the Magnaflow #12259 and I got it for $34 on Amazon. It's now $62. The Jones Max Flow series looks to be identical to the AP Exhaust. Even their model numbers are similar. They're about the same price after shipping (Summit, Jegs, etc.)
https://www.summitracing.com/parts/jex-mf1259
The 22" I later added to quiet it down after removing the cats is the AP XS2579, a clone of the Magnaflow #12579. The Jones version is the MF2579, but the AP is about $20 cheaper ($61 on Amazon).
Magnaflow, Jones and AP all advertise as constructing their mufflers with 409 stainless. I couldn't find what packing is used except for Magnaflow, which was stainless (like steel wool) wrapped around the core then fiber ("fiber glass") filling the rest.
For less than what you'd pay a shop to weld it all in, you could buy a $140 flux core welder from Harbor Freight and do it yourself plus have a new, very useful tool. Or, splurge for the $220 one (if you have a 240V receptacle) and have a lot more power and be able to run gas if you progress to that level.