Pump the brakes! Don't go to LSxKilr. The place you want to go to is KC Maxx Performance. The owner is Ryan Mitchell. He was previously the GM tuner at LSxKilr and is the only reason they have a reputation for tuning GM cars. He now owns his own shop (rightfully so). He will do a great job of tuning your car. I can confidently say this without even knowing what configuration you have. If you care about both power and drive-ability, he is your guy.
I made the mistake of taking my car to LSxKilr before knowing he had left. They wasted a LOT of my time and money monkeying around with my car. I took a run of the mill LS1 car that had a 243 heads, mild cam, and fuel pump swap that otherwise started, idled, and drove just fine and they gave me back a car that couldn't start, idle, or run right after 5 hours of jacking with it. They blamed it on the car and recommended parts to check/replace. If you find my build thread, you'll know that I went through this entire car with a fine toothed comb prior to this so having to spend a lot more money and time replacing parts was hard to swallow. I complied, limped the car home, replaced the parts, and took it back. They still couldn't get it to run right after another 5 hour round trip and 5 hours of jacking with it and continued to blame it on the car.
I wised up, did some digging, and found out about Ryan and his new shop. I took the car there. He had to completely redo the tune. It only took him 2 hours to fix my car. It starts, idles, and drives better than it has ever before. It drives exactly like stock all the way down to 1000 rpms even with 10.8:1 compression, 6.5 degrees of cam overlap, and a manual transmission. He even took me with him during the drive-ability tuning so he could make sure the car ran and drove to my liking.
The insult added to injury in all of this? LSXKilr refused to give me all of my money back. I had to argue with them to get back what I did. I paid for a service that I didn't receive, wasted lots of money and time on parts that didn't need to be replaced, and they basically told me to suck it up.
Summary, just take your car to KC Maxx Performance if you want your car to both make good power and run and drive right. If you just want a happy dyno printout, take it to anyone else.