Mach One seems to be a model of BMX made by GT.
Their numbering system seems to be
- S - Company that made the frame. K would mean Kinesis, but Robinson, Dyno, Powerlite and Auburn also made GT frames. Not sure what company is represented by which letters.
- I - Site/location that made the frame. This is an optional field.
- C - Third letter of alphabet, so it was made in March
- T - 20th letter of the alphabet, so it's year is 1980 +20 == 2000.
Your bike was made in March 2000, and probably took a few months to arrive at the retailer whence you bought it.
From https://bmxmuseum.com/bikes/info/122/ and others.
You can see 31 "Mach One" BMXs in this search
Now the bad news - a Mach One has "M1" stamped on the BB by the serial number. Yours doesn't, so it might not be what you think it is.
You can try registering your GT bike at https://www.gtbicycles.com/can_en/bike-registration by entering the serial and your email address. See what they can tell you about it.