look Fred, i changed the last few days the catalyst with a 200cell HJS. By mistake, they placed at the end of the catalyst a 2in tube! and go until it link up with the rest of the exhaust witch is build with a 2.5in tube.
I found out a significant increase of torque at the mid range. I thought that this increase was the 200cell.
Any way, i found out the sh1t they did with the 2in tube. Went back, after 3 or 4 days, they change it with a 2.5in. When i left the shop i immediately understood the lack of torque that i had beofore with the 2in, but much better with the oem catalyst.
and i said to my shelf Fuk... #%&$^%$
i don't Know man, have they test it a lot or....this just do the job fine!!!!