I am currently in the process of getting a new exhaust, as mine has decided to fall apart. My03 sti type uk ppp is currently running at 350bhp that has been mapped by Andy Forrest. It has a prodrive cat then 2.5inch cat back with ninja 2 back box. I am wondering if I should stick with 2.5inch or can I go 3 inch without needing another map?? Cheers

 

if you go 3" map will need adjusted stick with 2.5" better flow quicker spool up, 3" for making big power its not needed

 

Cheers also if I changed to decat, would I also need to get it adjusted as well???
It's a long way back to Scotland and don't fancy it till other mods are done at the same time

 

Better flow and quicker spool? Genuine question. I'm running around 320bhp in my wrx classic.

 

yes decat would need it the map adjusted to suite the car to get its full potential out of the mods. better doing all you want then get it mapped to suite everything and drive easy on it until then with all of its mods as you dont want it over boosting or causing issues to the engine

 

I'm of the understanding that the spool time is mainly governed by the size of the turbo, diameter of the headers, up pipe and volume of the pipe work between the turbo, intercooler and manifold. Does the exhaust diameter have such a noticeable impact on spool time?

 

Cheers uk300scoob I will do all mods first then drive it up in the low boost setting that was put on the map, so no chance of it going over 0.6 of boost
Also can you get my ecu mapped for launch control as well ??