From personal experience id just go with an entire intake as opposed to just a filter.. i have a carbonio cold air in my 02 1.8T And i love it.. sounds great, you definetly feel the difference when you step on the gas, looks great obviously, & to go with that its a great set-up cuz its got a heat sheild all around it and im sure anyone with a 1.8T knows the turbo & exhaust manifold is right underneath the intake soo without an enclosed system you can look forward to sucking in hot air..