A bit of a warning - Blowing smoke is not looked too highly upon on this forum, so you can probably expect to get some harsh responses for that. With that being said, no, there is no pump you can turn up on these trucks. The fuel delivery from the injectors is electronically controlled. You can add a good 6-position chip which will give you a decent bump in power, but with the stock injectors on these trucks being as small as they are (96cc), you won't see a massive increase in power (or smoke) until you bump up to larger injectors.
A few tuners you could look at are:
Gearhead - these guys are actually against smoking, and their tunes are very clean (as far as an old 7.3 goes). It says right on their homepage that any requests for smoke tunes will be turned down. With that said, I have heard numerous good things about Matt's tunes. Gearhead Automotive Performance
Power Hungry Performance - Bill has been in the tuning business for a long time, and definitely knows what he is doing. I actually ran his tunes for about 10 months. I was very happy with them, the only reason I switched was because I wanted to try new tunes, just for fun. Power Hungry Performance - Phoenix™ Chip
Another good one is Tony Wildman. I have heard numerous good things about him as well, although last I heard he was fairly backed up and heard to reach, as his daughter is going her second round with brain cancer. I have personally met the Wildmans, and they are great people. I'd like to try his tunes some day... Tony Wildman Performance Chips
As far as harm to the tranny, it depends on what kind of condition it's currently in. My truck had a new tranny put in just under 50k miles ago. I run stage 1 injectors, a custom tuned 6-position chip, and a T500 HPOP, which should put me at roughly double the stock hp/tq (well, at least at the crank anyways... hopefully). Pretty much what I'm saying is I'm pushing quite a bit of power over stock, and have a very heavy foot. My trans is taking it very well (for now), and is still shifting and driving as well as ever.
As far as the catalytic converter, it depends on your state. Here in CO where I live, we have yearly emissions testing on diesels. So, I took my cat off, hollowed it out, and slapped it back on there, and passed emissions with flying colors, even though it's technically a straight pipe. The cat is just there for visual inspection now.
Oh yeah, I forgot to add earlier, get a 3" downpipe if your truck doesn't already have one. That, along with a good intake (the 6637 is a popular one) are some of the first mods that should be done if you're going to be looking for more power. Those, and gauges.