Fit a free-er flowing exhaust system

Turbo diesels don’t really benefit from exhaust backpressure like petrol non turbo engines do. So the less restriction the better for your oil burner is what you are after. So what does this mean?

Well as standard from the factory the pipework is 2.5inches in diameter and it is mandrel bent pipe which means that the pipe maintains its cross section on the bends rather than getting smaller, This means that the pipework on the original system is pretty good. Certainly the centre section on the 600 is pretty much as good as you are likely to get. However where the gains are to be had are at the front and at the back. Most diesel exhausts will only have one silencer box at the rear of the car. In contrast most petrol engines will have 2 silencers. Why? Well I think it was Dave Vizard that once said quite rightly that a turbo is a pretty efficient rotary muffler (silencer to you and me!). So our little turbo is keeping the exhaust pretty quiet to start with. Now to be acceptable to the public buyers diesels have had to become quieter and quieter. This has meant that the backbox whilst ok, is fairly restrictive if you want more power. The best replacement is a 2.5 inch straight thru design with any bends being mandral bent to keep the airflow as high as possible. This allows for maximum flow whilst still giving some degree of comfort when driving, especially on the motorway. Some people may believe that you can do without any silencer at all but in practice it is far too noisy and would soon get on your nerves on the motorway.

I’m working on an idea to give the best of both worlds in terms of performance and noise so keep your eyes peeled!

In preliminary testing my idea gave a car an extra 6bhp on the same dyno on the same day.