There are a few bits and bobs done with mine also but has been done correctly , n249 has been deleted and diverted , have boost gauge vac gauge battery gauge , lost some small amount of boost when I switched to a straight through exhaust and popped an engine light which sparked bank 2 o2 sensor , my guess is that the fumes are flying past it so fast that it can’t read it properly and throwing an error , I am to put stock exhaust on it again this week and chop the straight one into tiny pieces . Hks diverter valve , cone filter all those kind of extras , turns heads everywhere I go , shushushushu gear change we all love