I want to purchase the cold air intake for my Nissan petrol 3L RB30 and just wondering if this will suite my car?

Considering your enquiring about the upper manifold insulator to suit an RB30 engine, if you have a standard fuel-injected version of the RB30 engine, then this item would suit. If you have either the fuel-injected or carburetor version of the RB30, then our lower manifold insulator would suit as shown in the link below :

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI607

If you have a standard fuel-injected version of the RB30, then you can run both the upper and lower manifold insulators.