Upsolute is not a con, although I think that some have said that some of the distributors are questionable as to their ability to correctly "install" the chip. (I am not sure if they re-flash the ECU, either through the computer module's connector or by de-soldering it from the board-or even if that is what they do). I had no problem with mine.

The other choice is Powerchip.

The issue I had in going with the ECU upgrade is that here in Phoenix, the highest grade of gas is only 91. This was not a problem as long as the outside air temp was below about 70 degrees, which is only about 5 months out of the year. The other 7 months, the motor pinged. The warmer it got, the more it pinged. In the heat of summer with the A/C on, it pinged like crazy! But the car is faster with the chip...