What about the Grouppe-s headers, any idea how they sound??? And aren’t the headers, properly tuned, good for more hp and torque throughout the power band???

 

I haven't heard them personally, but I hear they should sound very similar to Cusco's equal length headers (which I also haven't heard, but are supposedly amazing).

 

Yes, this is true....headers coupled with a good tune, and a good turbo back will increase both hp and tq throughout the powerband.

Think of your (or any) engine as nothing more than a big air pump.....let me explain.

You have your intake, which brings air into the engine to be mixed with fuel for combustion, the spent gasses are then expelled out the exhaust ports of the head. From this point, the smoothest and most direct route out the headers/exhaust/tailpipe will allow the engine to push more exhaust at a much faster rate than a restrictive, or unsmooth exhaust path.

Basically, the faster your engine can pull air into it, and push exhaust out of it, the more efficient and powerful it becomes.

-Ted

 

someone from cobb told me if i installed a header, i would get "hella turbo lag"

however, i thought that more flow = faster flow = faster spool. am i wrong?

this is assuming the header would be tuned (cobb stage II)

 

Cobb may be still subscribing to the old notion that aftermarket headers aren't good for turbo Subarus. The reason early headers got turbo lag was because they were poorly designed for more flow, which actually slows the spool time because the velocity is reduced (if the same volume of air is being pushed). If you have a bigger volume of air to move, then it will move slower because there is more air to push.

Also, there is an issue of heat loss. If the air in the headers lose heat, they also lose velocity. Less velocity equals slower turbo spool up. So, you don't want a lot of flow, just the right amount. Thats why you need well engineered headers.

You'll need to be careful when selecting headers for the WRX or STi. Ask about things like horsepower gain and turbo spool up (unfortunately, I don't have enough experience to offer any advice on good brands to buy). Most do best with a tune as well.