Subaru WRX and STi Exhaust general info

Subaru WRX and STi Exhaust general info:

What should I decide upon before purchasing to narrow down my decision?
a. Sound level.
b. Exhaust tip(s) diameter and shape.
c. Catalytic converter issues with regard to your particular state’s emissions laws.
d. Outside appearance, straight back exhaust or angled exhaust?

What questions should I ask of the retailer or manufacturer before purchasing?
1. Will this unit mate up to the rest of my exhaust? Some exhausts will fit the stock exhaust, or must be fitted to a larger exhaust.
2. Will this unit throw a CEL? Some do, some don’t, so find out beforehand.
3. Does it come with new gaskets? It is always a good idea to replace exhaust gaskets.
4. Does it come with a CEL fix if needed and is it the right one? There are two unique electrical fixes, one for the 02/03 and one for the 04. The 05+ does not currently have an electrical fix.
5. Will this exhaust clear the rear differential protector, if applicable?
6. Does this exhaust drone? Drone is a term to describe an annoying monotonous buzzing sound generally heard during long highway trips. This sound can be more apparent with wagons, due to the lack of a trunk to deaden the sound.

If after installation, my exhaust drones, how do I fix it? Many users report great success by using audio sound deadening material in the trunk, back seat area, and/or underneath your vehicle.

What is some good background information about exhaust pipe fitment?
Generally speaking, there are two types of catbacks:
Type 1: It has a sliding flange designed to bolt up to the stock downpipe.
Type 2: It has a flat flange designed to bolt up to 3″ downpipes.

Generally speaking, there are two types of downpipes:
Type 1: It is designed to bolt up to the stock catback and other type 1 catbacks.
Type 2: It is designed to bolt up to only type 2 downpipes.

Type 1 catbacks do not bolt up well to type 2 downpipes, and type 2 catbacks do not bolt up well to type 1 downpipes.
Type 1 catbacks and downpipes taper to 2.5″ where they meet.
Type 2 catbacks and downpipes are full 3″.
Type 2 downpipes are usually less expensive than type 1 downpipes.
Type 1 and 2 catbacks are relatively similar in price.

All 2.5″ catbacks are type 1.
Some 3″ catbacks are type 1, and some are type 2.

Share