yup...4g13 need more back pressure 2 back up its weak engine...a s-flow muffler will help also....
altho the 1.8" is big but can keep it 4 future upgrade like changing 2 4g15 block...rm 400 can kau tim edi
altho the 1.8" is big but can keep it 4 future upgrade like changing 2 4g15 block...rm 400 can kau tim edi

