How do they decide if the brakes are strong enough? As far as i know the standard Murena brakes can lock up all wheels, even on dry roads... And correct me if I'm wrong, but upgraded brakes won't help much when the friction between tires and ground is the limiting factor...
Well overheating could be an issue that will improve with upgraded brakes, could be the reason?
The only reason to upgrade to larger brakes is to avoid overheating. If brakes were cooled with indefinite sources of liquid nitrogen or something similar, we could do with bicycle brake discs on our cars!

According to the law of dry friction, the amount of braking is effected only by the load on the brake pads and a magic number called the 'coefficient of friction'. That number is a constant (in basic physics class at least!), specific to the materials in contact with each other.
In reality it's a lot more complex!

And you are spot on when you are touching the subject of overheating. The problem is the constant, which changes with temperature. And when the surface temperature of the disc reaches 1000 degrees or more, the disc is no longer solid steel!

But in your case, I don't think you should worry. As you mention, the Murena brakes are sufficient, and if you use EBC green stuff pads you will have excellent braking efficiency and unless you are doing a very hard race, you won't have any problems. This is where bhp is more important than torque: bhp determines your speed, which will be the speed you will be braking from - acceleration in the low revolutions means little to how much brake effect you need. It just makes you accelerate quicker out of the corners

And the MoT guys won't worry either as the bhp number is unchanged with the new engine.
By the way, does anyone know if it's possible to install the rear brakes from the 2.2 on the 1.6 trailing arms?
No, I think the caliper mount points will be wrong.
And a short update on my project... Exhaust is know mounted, the system is build with the orig. cat and a backbox from a Volvo 740, which was the best suited box I could find in Biltema

It took me a looong time to get the system fitted correctly, with custom made rubber mounts aso but it fits nicely now

Congratulations! When I pass the exhaust section in Biltema, I always get the "I want to build something out of these things!" feeling

Perhaps you guys can help decide the best position for the air filter (intake)... For now I will be running a standard setup with an aftermarket air filter, but I need to find a good location so I get a good flow and if possible rather cold air!
Above the gearbox facing rearwards, as we have it on the 2.2's.
Later I'm going to install an intercooler (probably water cooled) and oil cooler to allow some tuning.
I'm aiming for 140 hp and >300 Nm... should be fun

Sounds reasonable - and fun!

- Anders