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Quantitative Comparison of Exhaust Systems
Since I'm shopping for a new exhaust, I decided to try and develop a quantitative way of comparing them. What I did was use Power Commander fuel maps to calculate a performance parameter that can be used as a relative comparison index. I'll refer to this as the Power Commander Exhaust Performance (PCEP) index. The assumption here is that the PC fuel map is correlated with HP and torque, with higher PC fuel map numbers correlating with higher HP and torque. If this is true, then the higher the PCEP index, the better the performance of the exhaust system.
The data I used was for exhaust systems on Softails mapped for Stage 1 ECU and SE Air Filter. All fuel maps were downloaded from the Power Commander website.
The results suggest this may be a valid quantitative analysis method. Trends seem to make sense, e.g., you would expect 2-1 systems to have good performance, and therefore, relatively high PCEP values; and this is the case, with Thunderheaders having the highest PCEP of the 2-1 systems evaluated. Also, when you look at the PCEP broken down into RPM ranges, the mid-range tends to decrease and the high-range tends to increase when you take the baffles out of the pipes. There are some surprises though. Two 2-2 systems had higher PCEPs than the Thunderheaders, and the SuperTrapp Mean & Meanest Mothers had higher PCEPs than the remaining 2-1 systems; and perhaps the biggest surprise to me was how bad the V&H Big Shots Staggered did -- they were the worst performing exhaust system (lowest PCEP).
Below is a hard to read list of the results (best I could do). Attached is the Excel file with an easy to read summary table and all the data. Since you are not allowed to attach Excel files, I renamed the file extension to ".doc". After you download it, rename it with a ".xls" file extension and you should be able to open it as an Excel file.
Results List from best (highest PCEP) to worst (lowest PCEP):
(First number is the PCEP index. Second, third, and forth numbers are the PCEP broken down into Low (750 - 2500), medium (2750 - 4500), and high (4750 - 6500) RPM ranges)
Vance & Hines Longshots 1918 743 705 470
SuperTrapp Meanest Mean Mothers (baffles) 1763 653 727 383
Thunderheader full exhaust 1746 687 569 490
SuperTrapp Meanest Mean Mothers (w/o baffles) 1618 627 542 449
SuperTrapp Mean Mothers (baffles) 1567 507 609 451
Kerker 2:1 exhaust 1558 469 571 518
SuperTrapp 2:1 (21 discs & closed end cap) 1548 575 504 469
SuperTrapp Mean Mothers ( without baffles) 1522 456 539 527
Vance & Hines Longshots (without baffles) 1437 628 427 382
D&D slash cut slip-ons 1263 391 497 375
Vance & Hines 2:1 Pro Pipe 1243 407 432 404
Cycle Shack Tapered slip-ons 1227 361 494 372
Donnie Smith Mini Guns 1150 333 413 404
Khrome Werks tapered slip-ons 1115 327 437 351
D&D full exhaust 1098 298 419 381
Khrome Werks slash cut slip-ons 1066 312 414 340
Vance & Hines Straightshots (w/o baffles) 1043 337 355 351
Cycle Shack Tapered "M" Sidepipes (1 3/4") 1022 313 389 320
Python 3 full exhaust 1022 313 389 320
Vance & Hines Shortshots (without baffles) 1015 352 322 341
Khrome Werks 2:2 full exhaust 981 260 367 354
Cycle Shack Tapered "M" Sidepipes (1 3/4") w/o baffles 978 309 358 311
Vance & Hines Straightshots 961 311 364 286
Vance & Hines long Big Shots (w/o baffles) 786 309 186 291
Vance & Hines long Big Shots 780 248 283 249
Vance & Hines Shortshots 734 349 284 101
Vance & Hines staggered Big Shots (w/o baffles) 658 183 179 296
Vance & Hines staggered Big Shots 602 154 203 245
