If not mistaken, original is 2" from the extractor to the muffler. But don't bother to alter it into bigger size as it will decrease your power, if you like to have a louder or more aggressive sound, change out the whole system. You can try PM "Semperfi" as he have the whole new complete set of HKS muffler original from Japan for GTT. This might help you to get better HP and more aggressive sound.
Guys, there will be a Modified Car Competition & World Cup Screening at Jalan SS15/4 this Sun from 8pm onwards. Approximately 100 car parks will be reserved for this highly anticipated event. So far, a few teams have...