So I understand that the HKS kit is CARB legal but while doing research in proving it was without a doubt to myself I came across this on the ARB website under approved aftermarket parts, "2003 to 2005 model year Nissan 3.5L 350Z (excluding 2005 model year 350Z Track and 35th Anniversary models)." So as long as you don't have an 05 you should be in the green, pun intended. This is probably posted somewhere on here but here's one step removed for the modcurious http://www.arb.ca.gov/msprog/aftermk...es/amquery.php provides full list of CARB approved parts for most cars.