01-09-16, 10:24 PM
There has only ever been one aftermarket header system that eliminated the EXUP without causing some kind of flat spot around 3.5 - 4.5k rpm. That was the Muzzy 4-1 with horizontal merge plate in the collector. No longer on the market and rare as hen's teeth in the UK.
Even the best 4-2-1 systems, such as Akrapovic, suffer a little in that rev range in order to deliver better power from around 5k rpm upwards. I would describe it as slightly softer power delivery rather than a flat spot.
The flat spot from the cheaper EXUP-less replacement systems is very noticeable and impossible to tune out.
Even the best 4-2-1 systems, such as Akrapovic, suffer a little in that rev range in order to deliver better power from around 5k rpm upwards. I would describe it as slightly softer power delivery rather than a flat spot.
The flat spot from the cheaper EXUP-less replacement systems is very noticeable and impossible to tune out.