ap72 & gearheadsforlife,
Sorry about the the inaccuracy I put in about the timing control abilities of the MS1, but ... I made a mistake. It will control the timing.
Regarding the price, I bought an assembled MSII with 3.57 PCB, assembled relay board, GM HEI conversion kit and cable for less than $650 shipped; junkyard TPI setup for $175; LC1 wideband $125, stock Corvette in tank fuel pump $55;injectors serviced for $100. I had to buy miscellaneous gaskets and lines, fuses and some wire for less than $100.
I chose the assembled units because after reading the MegaManual and talking to a friend that has built 3 units (and seeing two of them in action with turbo cars), I determined that the assembled unit was for me for the extra money. A 'man has to know his limitations' and I knew I would be in for a headache if I tried to assemble a PCB. And the assembled unit for a multiport setup with either turbo or nitrous control was as close to plug and play as I could find. I chose against the MSI for two main reasons, 12x12 tables vs the MSI 8x8 tables which allows for alot more control/tuning capability, and the room to grow with the MSII or MSIII vs MSI.
I recommended the MSII or MSIII to the original poster because of what he said he was building - turbo engine, and no assembly of the PCB required.
In terms of the serial port, a USB to serial port adapter is cheap - less than $30. I asked the same question of why not a USB port? I was told, by DIYAutoTune that is was because of the toughness of the serial port and/or the delicateness of a USB port. If it had a USB port and the port broke then the PCB would have to replaced or repaired....that is what I was told and it makes sense.
Again, SORRY for any misleading info - it was not my intention and I'll repeat that I AM NOT an expert on this system or any other - I was just offering my opinion and advice based on my experience - for what it's worth