I have a MY55 STI if i was to fit a new 3" cat back exhaust would i need a remap?

 

Standard exhaust size is 2.5" buddy, so you'll be changing the back pressure of the exhaust a fair bit.
You would probably not need a remap.
However if you decide to have one, i'd suggest doing a few more mods first, to make the map cost effective.

 

I have got a nur spec r on order which i think tapers down to 2.5", I will be getting other goodies in the near future and then getting it mapped when cash allows, just wanted to fit the exhaust if its ok rather than looking at a nice shiny bit sitting in the garage but if it is going to do any harm then i will wait. Thanks for the reply.

 

Fitting the mid section and back box can be done without a remap buddy. Just don't mess with the cats untill you are financially ready to mod/map the car to suit.
Just fit that for now and enjoy.
You'll soon be leaving your credit card near the laptop.........temp.....tai....tion!!!

 

Ok cheers you are not wrong about the credit card my list of bits required always seems to get longer.