Exhaust System for 335i

[stefman]

Wow! 3/4 of the group?

[kenntona]

I've read that besides downpipes, many BMW owners in the US either (1) decat, and/or (2) install H-pipe or X-pipe in place of the secondary cats. The theory of the latter mods stemmed on creating a crossover connecting the two sides of a dual exhaust system to balance the two banks of the engine. The H-pipe is good at balancing sound pulses between the two halves, but does little to promote "scavenging" because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved "scavenging effects" by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone.

Can I assume that H-pipes and X-pipes are actually redundant for the 135s/335s, since a straight through exhaust system with the least resistance is the optimal setup for FI cars?

[kenntona]

Originally Posted by kenntona

Can I assume that H-pipes and X-pipes are actually redundant for the 135s/335s, since a straight through exhaust system with the least resistance is the optimal setup for FI cars?

I am asking this because some exhaust companies like Eisenmann and Supersprint have X-pipe for the 335......... quite confusing leh......

Anyone?

[phil]

using my old school train of thought for exhausts. H or X are used on V8 cars to stop droning, some say it improves HP, im not convinced.

I am yet to see a GTR with an X or H, all straight through

If it were me, I would have straight through

[fasterthanferrari]

then add this for some real power...

[roversen]

Originally Posted by fasterthanferrari

then add this for some real power...

Can i know what is this for?

[phil]

gives you basically an open header, bypasses the entire exhasut system

[bac]

This is what saw from another website.
VWvortex Forums: ATP Virtual Exhaust System setup questions..

[Ahbengdriver]

Originally Posted by bac

This is what saw from another website.
VWvortex Forums: ATP Virtual Exhaust System setup questions..

Cool . Can install on 335?

[Azrielsc]

ABD, I doubt u want this on your car since u are already thinking that the miltek exhaust is too loud!

For the rest, this is another alternative: Race Ready Performance // Electric Exhaust Cutouts