Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_1522 ( "Engine" text, "Exhaust Ports" text, "Bypass Ports" real, "Bypass Boosters" text, "SPI" text, "Tapered Grind" text, "Number on cyl." text )

### Question ###
How many bypass boosters are there on the engine with slit exhaust ports and SPI is yes?

### Accurate SQL ###

SELECT "Bypass Boosters" FROM table_1522 WHERE "SPI" = 'Yes' AND "Exhaust Ports" = 'Slit'