Horsepower	Single Exhaust Pipe Diameter	Dual Exhaust Pipe Diameter
200-300	3"	2 1/4"
300-400	3 1/2"	2 1/2"
375-450	4"	3"
450-550	4 1/2"	3 1/2"
550-650	5	3 1/2"
650-800	-	4"
800-1000	-	4 1/2"
1000 plus	-	5"