Product Description One of the best performance options for the BMW 135i, our GT Series exhaust improves hp by up to 40hp and up to 100hp with the ESS tune. The exhaust system is a quad tip exhaust requiring some modification to the stock rear diffuser. Like all RPi exhaust systems, this one is 100% made in the USA, constructed with high quality T304 stainless steel and comes with RPi's Limited Lifetime Warranty.
