More 1GR Supercharger Questions

Hi folks,
It's me again, with my S/C installation. I just started the job with a friend. We've already installed the intercooler parts, just to have my truck still rolling for a couple of days. Next week we'll go on with the rest, but after consulting my dealer I'm really concerned about it.

I went to my dealer to see how much would he charge me for the ECU reccalibration but he told me that they have done a S/C installation once before (for a 2012 FJ that went to the 2012 Dakar and that they encountered many problems, like missfires, engine hard to start, and a kind of hesitating at lo revs. They've had problems with the ECU recalibration, so they installed a strange ECM with a switch that I cannot understand made it work. It sounds to me more like they didn't really know how to reflash the ECU or that the calibration was not available then.

After doing some research I downloaded the latest Techstream SW form www.techinfo.toyota.com and I bought a mongoose cable that is on it's way from Hong Kong. I can see that if the TIS is followed properly everything should work fine.

My questions to you are:
1. Did any of you have issues using a lower than 91 octane fuel? Something like 84 or 87?
2. Did anyone with a S/C go to a high altitude place (like 10K f.a.s.l.) and experienced engine trouble?

Thanks in advance