Harley-Davidson Performance Guide

EVO Exhaust System Testing

Maximum Horsepower Output

Very few riders will question the fact that a good exhaust system is required for making more horsepower. Trying to determine which is the right pipe for your bike can be a daunting task. Motorcycle Performance Guide is going to offer its experience in exhaust pipe testing and offer some suggestions for the average rider.

So which is best?

Below is the summary of testing done by one of the industry magazines. The test bike was an 80CID EVO style engine at 9.5:1 compression using a Crane Fireball 310 camshaft and a Mikuni HSR-42 carburetor. The engine is a very conventional "Stage 2" engine. For various exhaust systems, chart shows horsepower from 2000 to 5500 RPMs, average horsepower, maximum horsepower, street power ranking and maximum horsepower ranking.

Kerker 2-1

Super Trapp 2-1 20 disk

29" Drag Pipe

29" Drag Pipe w/screw

West Coast Chopper Hell Bend

RB Racing 2-1

V&H Straight Shots

Samson Long Shots

White Bros Porker Dual

Cycle Shack 2" Duals

Custom Chrome 2" drags

D&D Power Drag

Python 3

Jammer 2-1

Chopper Guys 2-1

Hypex 2-1

Bartels 2-2

Hooker 2-1

HD 2-1

2000

20.5

20.6

20.3

20.9

19.8

25.5

20.7

24.2

23.9

20.0

25.9

20.6

23.3

22.0

23.1

21.7

20.1

21.7

16.5

2500

28.1

32.2

34.2

33.6

31.9

25.1

34.8

23.3

28.0

34.5

31.1

33.3

34.1

32.3

28.3

29.0

34.6

32.1

18.0

3000

31.9

38.7

42.1

42.9

39.1

35.4

37.2

36.7

33.7

41.1

26.3

37.0

37.3

40.5

43.6

41.8

41.1

37.5

23.1

3500

50.2

52.2

45.6

49.1

46.5

50.1

48.1

52.2

50.1

49.4

31.2

49.4

45.9

53.7

54.5

53.1

47.3

50.2

36.6

4000

62.1

61.7

50.7

55.6

55.9

62.0

61.6

61.7

61.5

60.1

57.0

61.7

59.6

62.0

59.1

61.3

59.2

63.0

41.3

4500

70.1

68.6

61.1

65.0

64.2

69.4

69.7

68.6

68.0

68.3

68.9

69.1

70.4

66.2

62.1

69.1

70.0

70.9

39.9

5000

75.1

75.2

73.3

74.7

71.3

74.7

75.5

73.1

71.9

73.5

77.6

74.2

76.3

66.9

66.2

74.6

76.1

75.8

30.1

5500

77.0

78.7

79.7

79.3

77.0

77.1

78.5

75.3

74.1

76.6

79.0

75.0

79.4

65.9

72.2

77.8

80.1

79.0

35.7

Average Horsepower

51.9

53.5

50.9

52.6

50.7

52.4

53.3

51.9

51.4

52.9

49.6

52.5

53.3

51.2

51.1

53.6

53.6

53.8

30.2

Maximum Horsepower

77.0

78.7

79.7

79.3

77.0

77.1

78.5

75.3

74.1

76.6

79.0

75.0

79.4

66.9

72.2

77.8

80.1

79.0

41.3

Street Power Ranking

96%

99%

95%

98%

94%

97%

99%

96%

96%

98%

92%

98%

99%

95%

95%

100%

100%

100%

56%

Horsepower Ranking

96%

98%

100%

99%

96%

96%

98%

94%

93%

96%

99%

94%

99%

84%

90%

97%

100%

99%

52%

After looking at this table, you may think that the most horsepower is the best pipe. That isn't always the case. Maximum HP only occurs at one point in the power curve. When you are riding on the street, your engine is operating over a wide variety of RPMs. The best average horsepower or the Street Power Ranking is going to provide you with the most usable power.