ok cool, the ecu is reflashed for my k&n, de-cat and 2'5 inch bore exhaust system. Thats great i'll def get that done asap.Yep well worth while gains.
You don't ned a remap its just ideal to get the best out buy you need a map based on what your caar's requirments are not just a group N map which means nothing realy group N just means almost standard.
the difference it makes depends on how bad the original casting was mine was pretty bad and it made a good difference worth the price ben charges