BMW F chassis M235i / 335i / 435i SOUND GUIDE
Valvetronic Designs valved rear section
For those looking for a little bit more sound and the ability to control their sound level on the fly the best way to go is with the Valvetronic designs valved axle back. This is roughly 30% louder than stock. If someone is looking for a subtle bump in sound quality this is the best way to go. Having the valve open gives you nice pops and having the valves closed keeps that stock sound level
Valvetronic Designs valved rear section + resonator delete
Level two is when one has the valved rear section but want a bit more aggression. With the resonator deleted you get more pops and more aggression on the downshifts. With the Zf8 speed transmission, upshifts and downshifts are met with pops and farts. Deleting the resonator will increase the sound level by roughly 10% more sound than level one
Valvetronic Designs valved rear section + catted downpipe
Adding a catted downpipe is a great way to see big power gains as well as sound gains. When you change the factory 800 cell downpipe to a 200 cell downpipe exhaust tone changes drastically. The sound quality gets a lot more raw. The downpipe is the most restrictive part of the exhaust and upgrading it to a 200 cell race cat leaves your emissions equipment intact allowing you to pass inspection, but gives you incredible sound gains. It’s vital to have a valved rear section to be able to control when the car is loud and quiet.
Valvetronic Designs valved rear section + resonator delete + catted downpipe
For more sound, just as in level 2, deleting the resonator is a great way to get more pops and snaps without affecting drivability. As the resonator is a free-flowing section of the exhaust deleting it only makes the setup 10-20% louder than with it still in place
Valvetronic Designs valved rear section + catless downpipe
Go in catless is where things get extremely rowdy. Catless is not for everyone, it smells and you will have to find a way to pass emissions but it makes the car sound glorious. Deleting the factory 800 cell cat to free-flowing catless downpipe gives you the ability to push more boost and more power. When catless, the exhaust is extremely aggressive. With valve open be prepared for snaps on the shifts and pure sound on acceleration pulls.
Valvetronic Designs valved rear section + resonator delete + catless downpipe
Level six is the last and most aggressive level for the F chassis BMWs. This is a complete straight pipe and having valves is vital. With no restriction the exhaust tone is very motorsport, extremely loud and very aggressive. For those who want the most aggressive sound possible going and catless and removing resonators and mufflers will get you this raw sound experience but there are drawbacks with a catalyst downpipe the car smells and emissions is a concern. With this setup be prepared to see flames with a proper tune