Hollowing out the pre-cat didn't seem to make mine any more sluggish, but I do have a standard transmission. I do agree with you on the plugs, what a pita. Oh, and be careful unplugging and plugging in the coil wires, the plugs get brittle with age and will fall apart on you eventually. I'm probably going to have to replace mine the next time I do the spark plugs or change a coil.

2001 Sportage, TJ 106's, Everet spacers and bumpstops, Bilstein shocks on the rear, cone filter, Crager wheels, 235-75-15 Goodyear tires. Custom front winch bumper by Dave Scott. Currently DOA, but it is a work in progress.
2011 Kia Forte EX