PORSCHE RACING HISTORYKees Nierop (CDN)
1983 : Sebring 12 Hours - 1st overall : Riverside 6 Hours - 1st in class
19 March 1983 - Sebring 12 Hours - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 9 | Porsche 934 | 009 00030 | GTO | Wayne Baker (USA)/Jim Mullen (USA)/Kees Nierop (CDN) | Personalized Autohaus (USA) | 1st | 1st | 15th | 231 laps |
24 April 1983 - Riverside 6 Hours - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 9 | Porsche 934 | 009 00030 | GTO | Wayne Baker (USA)/Jim Mullen (USA)/Kees Nierop (CDN) | Personalized Autohaus (USA) | 5th | 1st | 18th | 181 laps |
19 June 1983 - Mid-Ohio 6 Hours - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 9 | Porsche 934 | 009 00030 | GTO | Wayne Baker (USA)/Jim Mullen (USA)/Kees Nierop (CDN) | WLB Racing (USA) | 24th | 8th | 13th | 166 laps |
21 August 1983 - Road America 500 Miles - IMSA - International Motor Sport Association
| No. | Car | # | Class | Drivers | Entrant | Pos | Class | Grid | Notes |
| 9 | Porsche 934 | 009 00030 | GTO | Wayne Baker (USA)/Jim Mullen (USA)/Kees Nierop (CDN) | Wayne Baker Racing (USA) | 18th | 5th | 9th | 98 laps |