I endorse the VX cam and sport exhaust; with an adjustable gear to time the cam at 5 degrees advance, I knocked a second off my 0-60 time. The sport exhaust is fairly quiet and just helps the engine breath better at higher revs.

Others have encouraged to stick with the stock Volvo coil, and for good reason. Very few 4-cylinder engines require a special coil, assuming the rest of the ignition system is in good shape - cap, rotor, wires, plugs.

The stock Volvo air box is actually well designed, so leave it installed. However, there are 2 performance mods to make. The first - which also enhances reliability of the AMM - is to remove the thermostatic element in the box which controls the flapper door. Disconnect the hose from the hexhaust manifold "stove" for good measure, and blokc the flapper (or remove it entirely, as I did) so only cool air enters the air box. While you have the box out of the car, follow the intake path plumbing to where the air enters, behind the grille near the driver's side headlamp. In the plumbing you'll find a plastic "trumpet" - this is just a silencer. Remove it to gain a little better airflow.

The last thing you can do - at risk - is to remove the screen which covers the inlet of the AMM, as this reduces flow significantly. Just bear in mind that even a petrified dead bug hitting the AMM sensing element at high velocity may cause it to fail... and they're not cheap (the AMM, not the bugs).