pros: it's cheaper, you'll keep the "burble" sound in your exhaust

cons: because it's not equal length, the exhaust pulses are at different times. Meaning they are not in a rhythm. this will yield less hp, and slower spool up compared to an equal length.


there aren't many that are equal length, because of the single turbo, horizontal opposed engine design.

 

It's very hard to make equal length runners for a single turbo wrx....Greddy probably figured if you want to make more power, just turn the boost up.

 

custom headders are divided into two grups cosmetic and race.. cosmetic are easy to install and look good... race headderson the other hand if they look good OK... the purpose is pure function... with the cosmitic one you look good and what racer wouldnt want a couple of extra horses... exhaust headders are made up of 4 components 1) header flange 2)primary pipes 3)secondary pipes 4)balance tube.... the header flange should be thick 3/8 or beter to hold the heat and not leak... the primary pipes should be equal-length and have long bend radii.. to alow max flow.. the collector (into the secondary pipes should be equal-lenth) and the secondary pipe in our subies is where the un-equal come into play.... you wont loose much hp if the primarys are the same.... look for a headder that has at least 6" of up pipe to stablize the rhythm pulses... also look for a Stainless Steel it is the way to go for Turbo.. Cuz it holds the heat in the pipe and gets the exhaust gas flowing faster that a cooler steel pipe... hope this helps you in you search for a good headder....

 

you are very welcome