ET is so dependent on the driver's skill (especially on a six speed) that it is almost irrelavent as a means of comparison. I have seen stock Supras run 14s with a poor driver, then the same car run low 13s with a good driver.
MPH is a better judge of your car's performance as it is not nearly as dependent on the driver's capability. Judging by your 60', you have a pretty good handle on launching your car, especially if this was done on the stock 255 x 45 x 17 tires. Your mph seems a tad low, but this may be because of temperature, humidity, altitude, etc. My Supra typically ran 104 to 107 mph depending on weather, and that was at 33' above sea level. But it is an auto, not a six speed.
The speed is in line with the HP #'s I dynoed at, around 270 rwhp. This is an auto. There was another BPU+ supra at that has dynoed over 100 hp higher than I and he was only doing about 113 mph with ETs in the 13 to 13.5 sec range.
These numbers still seem low to me. Your altitude and teperature are similar to where I live, but BPU auto Supras out my way virtually always run between 115 and 120 mph and et from mid 11s to mid 12s. Stockers typically run low/mid 13s at 106 mph. Have you done compression tests and checked for boost leaks? We generally run our BPU cars between 17 and 20 psi, with 18 or 19 seeming to produce the best ETs.