Many people have midbox chop on there 250 (I did too) some even done the rear box, both sound great in there own way (we have all watched the many vids) my issue was once my miltek decat was fitted car became abit too roar under heavy acceleration (bike type drone), there are many very good exhausts on the market but I fancied a custom job as I have no issue with the back box just the missing resonator and extending the 3" a bit so i Had a custom exhaust done this weekend I have had 3" from flange@decat to a small resonator to the rear of the under tunnel then the 2.75 to the standard backbox. Works spot on not restricted like it felt with the factory resonator, and not ott like having decat and midbox chop. Sounds as the car should imo.
I've been looking into this a lot more recently in preparation for the Hybrid, Seems sticking with the 2.5" pipework keeps you from loosing low down power and torque and is good for upto ~340bhp. Im running a 2.75" decat with the stock system minus the midbox and a smaller rear box and it seems like it should be more than capable for now.
Exactly Jamie I opted for the extra bit of 3" but added a small resonator as alternative to running 2.75 without the resonator at all and seems to do the trick deeper sound than non res without droning. The car was mapped with the 3" and it's so short there there would be min loss imo but valid point on the torque, I do still have my dyno graph so will run it again in a few week see if any curve change. may just be me but the spool seems improved.
I guess you mean below 2500rpm before boost comes on? after boost comes on, smaller pipes should have the opposite effect..
I honestly couldn't tell you but from various people in Oz running different setups and actually testing them in the RR along with Damien from Inoxline's help with various systems, 2.5" seemed to be the best in terms of performance
hmmm, forgive my asking have you got any idea is there any aftermarket system which is not restrictive but as quiet as the stock unit? I understand it sounds stupid but I have been playing with my 205 for 20 years, from stock to now Mi16 overbored to 2.0, throttle bodies, fast road cams, ecu..... I now want a fast car but very quiet.
TBH many of the aftermarket systems available can be had with the large middle resonator which will help keep the noise down. Fitting a sport cat over the decat should help keep it at a sensible level as well. I would have a look at the Inoxline system with both boxes in it. Won't be as restrictive but shouldn't be loud either.
That's primarily why I opted for the supersprint system as it's 2.55 inch. Also temped for the decat but don't want the drone......
Going by me having a decat on my R26 there's no drone at all just louder on full chat and slightly louder on idle might be different on the mk3 though
The drone comes from deleting the middle resonator and having decat at the same time, I think the mk3 is a tad louder than the mk2 in standard form due to the diff in backbox
