Recently available from SARD is their "Sports Catalyzer", or high flow cats. Sadly, they're relatively high price and lack of a US-based distributor would put them out of reach for many.
They also have a relatively simple short-ram intake on the market that retains the stock rubber intake hoses.
Some other unrelated SARD race goodies for you
Battery relocation box
Radiator hoses (Z34 application available)
Fuel surge tank
Fuel return tank kit
Radiator caps
