I got a v2 sti import, it has a stainless system which is decat 3 inch pipe straight through.
im not that happy with the noise it makes and was considering getting a replacement scorpion system which i believe is 2.5 inch straight through.
Will it need remapping if i change it? im running an Apexi ecu and a 20g turbo

 

Malpas Wales ?

Get a H&S Original Scooby Sport BB with a 3" bore/flange and all will be well. If you go 2.5 it will need tweaking.



I have one on mine and it is vastly quieter than my original 3" Apexi N1.

 

Malpas cheshire.
Cheers, just want somethin that looks mean but has a nice deep tone instead of a neighbour waking roar

 

Mine has antilag so this is it at it's loudest...

http://www.youtube.com/watch?v=bQLJH99eLC0

 

Yes it will

As you will be restricting the exhaust flow out of the engine. (more backpressure)
You will need it remaped and you might see a backward step in performance.

If you want it sound better
Your best plan is to keep the existing 3in downpipe and center section and change the back box. If you go this route you will change the sound and will not need a remap.

Steve

Just re read you post. By straight through. Do you mean a complete one piece exhaust or decatted