wont make one but of difference to the engine just means the smoke in the exhaust will have a shorter route to go before its out of the exhaust!good few people running them on here!dylans right about nct doubt it would pass!but just swap it with a standard or whatever for nct if you wanted to!seeing as the exhaust is alot closer to you when driving it it will make it seem louder to and there will be more in car noise!