F series M3/M4 exhaust modification
The process for the exhaust is the same on all the different models, even the competition pack versions as the exhausts are 99.9% the same, only the competition packs crackle more due to the factory map. (see further down for the opf/ppf/gpf model)
the process is to take the full exhaust off the car and remove both secondary cats (still passes MOT with primary cats) and replace with stainless steel 2.5" pipe, then delete the small resonator leaving the H pipe section and finally creating a partial bypass in the rear silencer (the latter two parts of the mod are done by opening the sections from above and modifying internally so no evidence is visible once welded back together and system put back on the car)
the flaps still work and are still very relevant, so flaps closed still gives you a quieter tone than flaps open, though both options are louder overall.
I've had no complaints of drone with flaps closed but still gives you a lovely aggressive noise once in M2 flaps open.
This mod is £300
here are some videos of the mod, first up here is a competition pack, first on a dyno and secondly driveby:
Next up we have a couple of vids of the standard exhaust once modified :
The clips really don't do justice to the results, more videos and reactions can be found on my instagram:
The opf/ppf/gpf model differs as it now has two filters, these are M4s built july 2018 onwards till the model was replaced by the G series.
on the opf model you have 2 options, either secondary decats, resonator v2 and backbox modified or resonator v3 and backbox (v2 is less complicated than v3, as v3 is to get it closer to the same volume as removing the cats, which some people arent comfortable with, v3 also sharpens the crackles and gives it a more V6 like tone, its basically the equivelant of the equal length pipes you can get)
both options are £390 and again all looks standard from underneath with valves working as before.
ppf m4 video below
please check out the facebook link for reviews of my work, I guarantee my work for the lifetime of your ownership, all parts used are high quality stainless steel including the welds themselves, no issues with warranty or MOT, please contact the number below for any other questions :)