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I installed a Works Stage 1 Turbo kit on my 2013 FR-S, June 2015. I used the ECUTEK tune that was provided by Works Motorsports. The only modification that I have done before turbo installation was a flex fuel kit tuned by Delicious Tuning. Per dyno results, flex fuel tune was providing a 169 whp on E66 NA. Compared to turbo kit (running on California 91 octane) it definitely delivers more power than prior flex fuel tune. I could feel the pull from 3100 rpm up to redline. For a turbo kit that does not have the traditional large intercooler this kit is amazing. The car feels completely different.
I was going to install an AVO kit that I bought used. The used kit was missing an oil pump plate. I requested to pay this missing part from AVO but totally ignored my request. I could have gone to a machinist to fabricate one for me but decided not to go with the AVO turbo kit and sold AVO kit to someone else.
The reasons why I selected this Kit over others:
1) It's a turbo
2) I don't get to touch the bumper
3) CARB legal
4) I could upgrade to a gtx2867, gtx29 or may be even a gtx35
5) It's not a supercharger
I also installed a PCV Mishimoto catch can, Radium crankcase catch can and a Tomei uel headers.
I purchased a "Flash & Go" tune from delicious tuning plus 11 psi map sensor. Dyno results are down below. Dyno was done on DYNO DAY (08/30/2015), at Church Automotive Testing.
"Flash and Go" tune was disappointing. On E85, no matter what ethanol percentage, the car would hesitate, be rough going, sputter and not go at all below 3,000 rpm, from stop to go up sloped. From stop to go turning left on an intersection would be a problem as well. I would have to push both clutch and break pedals, rev pass 3,000 and then release the clutch and break so that I could make the car go. On pump gas, it would run good. I discovered on DYNO DAY what the problem was. The car was running lean below 3,000 rpm. I was told by Church that lean condition can be corrected with a DYNO tune. Dyno tune will have to wait because it will cost me approximately $850.
Overall I am more than satisfied with the kit and base tune provided by Works. I am getting used to the power that the kit was able to provide and plan to upgrade the turbo later. For now I will upgrade to kit with a water intercooler and get a tune via Church Automotive Testing. No more E-Tunes for me. There goes over $450 down the drain.
Comments added on 09/15/2015:
Had a 2:00 pm appointment today with Bill at Delicious Tuning. He was able to identify the problem. For some reason Bill thought that the Flex Fuel kit was a Delicious Tuning Fuel Kit. DT Flex Fuel kit uses the rear O2 sensor. My FF kit works by wire tapping the white/blue wire on the ECA harness. As soon as Bill realize that was the problem he changed the flex fuel tune to utilized the signal coming from white/blue wire on the ECA. Eureka!!! No more problem. It was a quick fix. It took less than 30 minutes. After Bill re-flashed the ECU, I test drove the car on pump and on flex fuel (E55). It was smooth and powerful. I can't confirm if I still have a lean condition but by the way the car is performing I'm optimistic that the car does not have a lean condition. Drove the car over 2 hours from Escondido to Encino, CA, did a couple of WOT and did not find any problems. Nice job Bill!!! 
