This weekend in Montreal almost every team will be introducing aerodynamic changes, with some teams going a lot further than others.

The Canadian circuit is, in many ways, the first really low-downforce track the teams have visited this season. However, under the new testing rules, the teams have not been able to run their new aero components since Paul Ricard, and since then the FIA has 'clarified' the rules regarding rear wing flexing.

The Montreal circuit can be considered as including no high-speed corners, as turn 5 is taken comfortably at full throttle in fifth and sixth gears. The primary focus for the aerodynamicists is therefore on minimising drag levels in order to achieve competitive straightline speeds (with a maximum over 320 kph), while the downforce will assist vehicle stability under heavy braking, as well as in the slow-speed chicanes. The low downforce levels mean the car feels light to drive, and nervous under braking. This means the drivers need to be more delicate with their steering inputs, and when applying the brakes and throttle.

Ferrari will use new front and rear wings, first tested at Paul Ricard before the Monaco Grand Prix. The F2007 will also boast other minor aerodynamic modifications.

McLaren will be running what it describes as a Montreal-specific aero package, as is BMW, while Toyota, eager to make up for the misery of Monaco, is relying on a medium/low downforce package, which consists of new front and rear wings and a number of other small changes. The Japanese team, like many of its rivals, will need to make full use of the Friday practice sessions as it will be intending to use a similar package one week later at Indianapolis.

Adrian Newey summed up Red Bull's approach to Montreal: "Like most teams we will be focussing some attention on our brake ducts and also running a smaller rear wing. We also now have to comply with a new Deflection Test introduced by the FIA to ascertain if your rear wing is flexing illegally.

"We tested our Montreal configuration before Monaco. The rear wing we ran at this test was a cut-down version of our Melbourne wing, so Montreal will be the first outing for our definitive low downforce rear wing."

'Sister' team, Toro Rosso, will be running new front and rear wings. "The front wing also requires new bargeboards and all these items will have their first track test on Friday," revealed Giorgio Ascanelli. "For now, we're having to trust in our wind tunnel data."

Honda, which is desperate to open its 2007 account will be introducing a number of new aero components as well as some "mechanical improvements".

Spyker will also be looking for an improvement, but with its own Brackley wind tunnel not coming on line until this week, the changes will not be as significant as at some other teams.