Below are some pics and a dyno sheet of my Underground Racing bolt-on twin-turbo Gallardo.
The 651 rwhp dyno was with pump gas at 4 psi. The 814 rwhp and 950 rwhp runs were with race gas at 8 and 10 psi, respectively, as shown on the dyno sheet. For just driving around, I'll probably leave it at 4 psi. In any event, I think it's safe to say the stock motors in these cars respond dramatically to boost!
My overall experience with Underground has been superb. By way of background, I had never done any business with Underground before this project, although I've had numerous high performance cars, including a couple of FI Vipers, a Z06, several AMG Mercs, etc. I ran Jason Heffner's supercharger system on my GTS for a while years ago, and later when I decided to upgrade to twins, I had Jason do the install. My experience with Jason was great, and I have talked to him several times since I bought the G, so I knew sending my car to him was a good option. I had also talked with Doug Levin a few times about my Vipers, and had bought a few Viper-related parts from Doug, so I knew Doug was a great guy to deal with as well. I had actually talked to Underground about doing the twins on my Viper before going with Jason, but at that point Underground was new to the Viper scene, which is the main reason I went with Jason. Now that several years have gone by, and several people I know have had their cars done by Underground, Heffner and Underground are pretty much Coke and Pepsi in my mind, which made the Underground option much easier. DLM may be more like RC Cola--a great product with a devoted group of followers, but one that flies a little below the radar compared to the other two. So I'm not here to throw rocks toward any other tuner.
In any event, Underground has been great to deal with, extremely professional, and they have done everything they said they would, when they said they would. They did the build in just over 2 weeks, which was a big reason I went with the bolt-on setup for now, because I didn't want the car down the rest of the summer. I'm not sure how they pulled that off given that the shop is bursting at the seams with Lambos, Vipers, etc., but they delivered. Communication has been constant, and I have to say when I got the pics below of the build, it was really hard to believe that was my car!
When I arrived to pick the car up, the car was freshly detailed and spotless inside and out, and after Kevin and I went for a drive, Kevin and KC went over everything with me (how to operate the boost controller, etc.) and answered all my questions. I also had an opportunity to talk with the technician who did most of the work on my car, and was very impressed. One of the things that helped me decide to send the car to Underground was the fact that I had an opportunity to visit the shop several weeks ago and observe what was going on. The entire operation is very impressive and professional (clean, well-organized, etc.), but the thing that impressed me the most was the techs--the guys who are doing most of the fabrication and installation of various systems, etc. To say that these guys were different from the typical automotive tech at a dealership would be an understatement. I realize this is a personal opinion, and my intention isn't to knock all dealership or other automotive techs as there are certainly some good ones out there, but these guys projected an air of confidence and professionalism that I hadn't seen before in an automotive environment. I mentioned my impression yesterday to Matt, the tech who worked on my car, and he answered simply, "It's a passion. We love what we do, and we treat customers' cars like we would treat our own." And that in a nutshell is the impression I got several weeks earlier from hanging around the shop for a while. Kevin and KC are really fortunate to have guys like Matt as part of their team.
The install looks even better in person than it did in the pictures (of course!). It looks like something OEM IMO. But even better is the driveability. It is not similar to stock, from what I experienced; it is stock. I drove the car the almost 4 hours back home including some very heavy traffic, a couple of stops, etc. and noticed nothing at all any different from stock, with the exception of some cool hisses and whooshes coming from the engine compartment occasionally . Outside temps varied between 85 and 97 with high humidity, but the water and oil temps and oil pressure all read basically the same place they did before, and stayed there. In short, I detected no driveability issues whatsoever. No idle issues, starting issues, no nothing. Maybe I'll have a hiccup of some sort sometime, but not so far.
There is one other thing that is different, however, and that is the exhaust. I was curious about how the car would sound with the addition of turbos and the X-pipe, deletion of cats and the factory muffler, etc., and I have to say it is just about perfect for me. The sound is similar in tone to the Tubi I had on the car, but maybe 30-40% louder at moderate to WOT, which is just right as far as I'm concerned. But even better is this exhaust doesn't appear to have the drone or resonance that the Tubi sometimes had at cruise/low rpm. The car definitely seemed quieter at interstate cruising speeds than it did before.
Overall, the delivery, like the rest of my experience with Underground, was handled very professionally. I'm very happy with the build and looking forward to putting some more miles on the car!
Underground Racing Bolt-on TTG 
Linear Mode
