PORSCHE RACING HISTORYMike Downs (USA)
1973 : Daytona 24 Hours - 3rd in class : Sebring 12 Hours - 2nd in class
4 February 1973 - Daytona 24 Hours - World Championship for Makes
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 77 | Porsche 911 S | 230 1687 | GT+2.0 | George Stone (USA)/Bruce Jennings (USA)/Mike Downs (USA) | Silverstone Racing (USA) | 4th | 3rd | 32nd | 638 laps |
24 March 1973 - Sebring 12 Hours - Non Championship Race
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 76 | Porsche 911 S | 911 230 1687 | GTU | George Stone (USA)/Mike Downs (USA) | Silverstone Racing Team (USA) | 8th | 2nd | 23rd | 209 laps |