Actually I had Lingenfelter do the upgrade to my LT1 just over a couple years ago. I just had them do the top end upgrade to my 350. I had them install Kooks long tube headers as well as welding in a set of subframe connectors. They definitely aren't fast in their work but they are very thorough and did a great job with my car. I had a small oil leak pop up just after getting it back, and they were quick to address the issue and fixed it under their warranty. It starts up first time, every time, idles smoothly and it drives almost like a stocker... until you step into it. THEN it really wakes up and takes off. I got a little over 100 rwhp gain in my car, but is still very streetable and dependable. I'm sure you can get more overall horsepower through other sources, but with their dyno tuning afterward, you'd be hard pressed to find a better running, smoother car with these mods from other shops. I would do it over again if that helps answer your questions. Thanks
Jeff