I'm tuned by Bren.
353whp / 407wtq @ 20psi on a stock VF43 turbo. Too many mods to list, but the important ones are a built block (only pistons), ETS TMIC, APS TBE, Cobb SF Intake, and an Invidia EL Race header. The car is prepped to run in SCCA Street Prepared. It's my daily driver and has won multiple SCCA events at both the local and national level.
I have run custom tunes from other shops with varied success. After having the car tuned by Bren, I noticed several improvements. While the newfound power was nice, the biggest improvement that I noticed was how smooth the car was. This includes both low speed bumper-to-bumper traffic, and high speed WOT pulls. The car runs MUCH smoother than any other tune I have ever run. One thing that I really like about Bren is that he will happily go out on the road with you after a dyno tune, and make any needed tweaks while you drive your own car how you normally would. This creates a real-world condition for him to help fine tune things.
Overall the car feels MUCH better. It now pulls extremely hard, and 6th gear now feels like 5th, and 5th feels like 4th, etc. In addition, I'm able to modulate the throttle and boost in a much more controlled manner. For example, on my old tune my car was practically like an on/off switch. If I gave the car 40% throttle I wouldn't have much power/boost - but if I gave it 41% throttle, I'd instantly have 15psi of boost/power out of nowhere. There was no concept or feeling of partial boost (ie: below peak)- it was either there full bore or it wasn't. Now I'm able to hold that 40% throttle, and actually get the correct amount of boost for that target. On top of all this my peak boost is now 20psi, compared to 21psi on my previous tune. I made much more power overall, with 1psi less of boost.