GESI actually has Gen1 300 & Gen2 400 cell cats, different rating and pricing to fit any budget and flow appropriate for 350-550hp as well as models for 550-850hp (larger OD body).
100-200 cell cats are generally so cheaply made that actually flow significantly worse than 300-400 cell good quality cats. Those 100-200 cell are more “fake it” than actually controlled emissions/smell.
Nothing I’d use for Mk7, but GESI makes Gen2 cats rated for 1,200hp per cat so don’t kid yourself about headroom there’s plenty to be had for any application.
HJS makes great quality, but far less common in the USA. The guys in Europe get most of ‘em