What's this about removing the cat hurts the low-end torque? The LT1 has huge torque everywhere. The cat is the single most restrictive part of the exhaust. On an engine moving as much air through the exhaust as the LT1 removing the cat would make a power gain noticeable on a dyno, especially at high rpm. I would suspect power to gain everywhere, but probably not more than one or two horsepower. The power and torque peaks would probably move higher in the rev range, but both measurements would go up.
I think instead of worrying about the exhaust you should try getting some better flowing headers. The stock manifolds on those engines are also very restrictive. If you want to gain easy power then that'd be a way to snag 10 or 20. Also, that engine is sucking in a lot of air. A better intake pipe and filter would make a difference.
A modification like headers and a test pipe wouldn't necessarily lower your low end torque. It would go up, but not as much as torque higher in the rev range. The stock parts certainly aren't making torque, they're just restricting it at higher rpm so it feels like its got a ton of low end grunt. If you slap on a bunch of flow parts the torque will go up everywhere along with power, but it'll go up a lot at high rpm.
EDIT: I guess I'm late to the party cause you already got headers. Anyway, look into that intake if you haven't already.
