I'm assuming from your vehicle description that you have the 1.9JTD diesel engine? If that's the case I'd skip induction kits look at a remap for the best gains. Although not always a problem, performance air filters etc have caused issues with the MAF sensors. A good quality (quality is key) remap plus EGR delete would give you noticeable gains in bhp, torque and eliminate the common sticky EGR issue.
I looked into into induction kits and after some time chose a remap and a larger intercooler kit. As all the air reaches the inlet through the intercooler this was the area I looked to modify. But beware, it's a slippery slope, this leads to that and a bigger this and extra that and before you know you have a rebuilt motor. But I digress, I'm sure our fellow AO's will provide you with more choices and options http://www.alfaowner.com/Forum/image...ies/thumbs.gif
Thanks .....but i have bought a induction kit and i need to work out how to fit ...anybody ?
Depending on how big the filter is you might be fighting for space in the engine bay. The normal setup is made up of the airbox which lives under the battery, you'll see the snorkel pipe rising up up off it with the opening bolted to the slam panel near the bonnet catch. The main issue is that due to the position of the airbox and the piping you get with most induction kits means you'll be sucking in hot air from the engine bay, you really want cold dense air from the outside so if you can use some silicone piping you might be able to place the cone filter in the passenger side wing. But again, and I hate to be negative, I don't know what benefit it will be. But hey, now that you have it, give it a go and see what happens.
P.s. Best of luck, the GT engine bay is pretty packed with stuff so let us know how you get on.