How many bypass boosters are there on the engine with slit exhaust ports and SPI is yes?
{'header': ['Engine', 'Exhaust Ports', 'Bypass Ports', 'Bypass Boosters', 'SPI', 'Tapered Grind', 'Number on cyl.'], 'page_title': 'Cox model engine', 'section_title': 'Cylinders', 'caption': 'Cylinders', 'rows': [['Space Bug', 'Open', '2', '0', 'Yes', 'Yes', 'None'], ['Thermal Hopper', 'Open', '2', '0', 'Yes', 'Yes', 'None'], ['Space Bug Jnr', 'Open', '1', '0', 'Yes', 'Yes', 'None'], ['Space Hopper', 'Open', '2', '0, 2 side flutes in 1961', 'Yes', 'Yes', 'None, #4 on 1961 models'], ['Strato Bug', 'Open', '2', '0', 'Yes', 'Yes', 'None'], ['Product Engine', 'Open', '1', '0', 'Yes', 'Yes, No after Leisure', '2'], ['SureStart', 'Slit', '2', '1', 'No', 'No', 'None'], ['Babe Bee', 'Open', '1', '0', 'Yes', 'Yes, No after Leisure', '2'], ['Golden Bee', 'Open', '1', '0', 'Yes', 'Yes, No after Leisure', '2'], ['Black Widow pre 96', 'Open', '2', '0', 'Yes', 'No', '1'], ['Black Widow post 96', 'Slit', '2', '1', 'No', 'No', 'None'], ['Texaco', 'Slit', '2', '1', 'No', 'No', 'None'], ['QRC pre 96', 'Open', '2', '0', 'No', 'No', '6'], ['QRC post 96', 'Slit', '2', '0', 'No', 'No', 'None'], ['Killer Bee ‘96', 'Slit', '2', '1', 'Yes', 'Yes 1', 'None'], ['Killer Bee ‘02', 'Slit', '2', '1', 'No', 'No', 'None'], ['Venom', 'Open', '2', '1', 'Yes', 'Yes 1', 'None'], ['Medallion pre 96', 'Open', '2', '0', 'Yes', 'No', '1'], ['Medallion post 96', 'Slit', '2', '0', 'No', 'No', 'None'], ['Medallion 051', 'Slit', '2', '1', 'No', 'No', '7'], ['Tee Dee 049', 'Open', '2', '2', 'Yes', 'Yes 2', '4']]}