Harley-Davidson Performance Guide

Twin Cam 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 a stock EFI Twin Cam TC88-B engine  The engine is a very conventional "Stage 1" engine. For various exhaust systems, chart shows horsepower from 2000 to 5500 RPMs, average horsepower, maximum horsepower, street power ranking and maximum horsepower ranking.

Samson Shorties

Python 3

Samson 2-1

Rev Tech 1 3/4" Duals

Cycle Shack Duals

Dyno Power 1 3/4" Drags w/Screw

Dyno Power 1 3/4" Drags 29"

Hooker 2-2 Torque setting

Hooker 2-2 HP setting

Kerker 2-1

Super Trapp 12 Disk

Super Trapp 20 Disk

Jammer 2-1

Bartels 2-2

Screamin Eagle Pro 2-1

Part Number

S-153

DS-210431

C-111

59-166

PHD-140T

11-266

11-266

27611

27611

128-71450

New

New

280966

ET2060

64796-00

2000

24.1

25.1

25.8

24.7

24.9

23.2

22.4

24.6

23.6

25.2

24.9

25.6

24.8

24.2

25.4

2500

33.1

33.8

32.1

33.4

33.5

32.4

31.2

33.2

33.2

31.9

32.9

33.5

33.0

33.3

32.6

3000

40.4

40.9

40.9

41.0

41.3

41.6

39.7

41.9

41.6

39.1

41.5

41.2

40.2

41.6

40.8

3500

48.3

48.4

49.3

47.5

49.0

48.4

45.4

49.1

48.6

48.6

49.5

49.7

48.8

48.4

48.5

4000

53.8

56.0

56.1

55.1

55.6

54.1

50.9

55.4

54.6

56.1

55.8

57.1

55.1

55.3

54.0

4500

60.6

61.9

61.1

61.1

61.3

59.7

58.5

60.9

61.0

61.4

59.8

62.2

60.2

61.8

58.9

5000

64.4

66.4

63.2

64.7

63.8

63.3

63.1

64.3

64.9

65.2

63.4

65.7

62.8

65.1

61.4

5500

65.7

67.2

64.8

65.6

65.6

64.4

63.8

66.0

66.7

66.1

65.9

67.4

64.0

66.7

63.3

Average Horsepower

48.8

50.0

49.2

49.1

49.4

48.4

46.9

49.4

49.3

49.2

49.2

50.3

48.6

49.6

48.1

Peak Horsepower

65.7

67.2

64.8

65.6

65.6

64.4

63.8

66.0

66.7

66.1

65.9

67.4

64.0

66.7

63.3

Street Power Ranking

97%

99%

98%

98%

98%

96%

93%

98%

98%

98%

98%

100%

97%

99%

96%

Maximum Power Ranking

97%

100%

96%

97%

97%

96%

95%

98%

99%

98%

98%

100%

95%

99%

94%

 

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.