For some time, I have been thinking about making my CLS 55 sound a little more V8. It’s too quiet at lower speeds (almost inaudible in town speeds), and properly audible only at quite high engine speeds. I heard an E55K (Adrian’s) at Bluewater which had had its center silencer removed – sounded great. Planned to hear it on the move, but never got round to it. Decided in the end to ‘just do it’. Ian (flanaia1) recommended Exhausts UK Custom Stainless Steel Exhausts. I called them and explained what I wanted. They did a bit of research, and told me I need a X pipe as the center silencer that was being removed performed the “balancing” of the 2 banks of cylinders. We agreed a price, and a date (on the way to Scotland for the Scottish hoon) for fitting. They assured me they used the highest quality stainless steel (304, whatever that means) and TIG welding (also supposed to be industrial strength). They estimated that it would take about 2 hours, as they had to make the X pipe with the car present. exhaustsuk are about a 10 min walk from Mercedes Sheffield. Where is the battery? When the car was first on the ramp, we could not find the battery (needed to isolate it). It was not in the place you expect it to be (i.e. to the right of the spare tyre well). The manual stated that the battery is to the right of the spare tyre well. We didn’t know where the secondary battery was either. We could not see a battery anywhere in the engine compartment. Scratching our heads for a while, I noticed that there were 2 coloured round things near the rear of the spare tyre (I don’t have a spare tyre, so I have an additional storage compartment under the boot floor) compartment. We unscrewed those, removed the moulding for the additional storage compartment, and there was the large battery lurking .. parallel with the rear axle, and about 6 inches behind the rear axle. I like to think AMG did this for improved weight distribution. Designing the X pipe It turns out that there is a balancing pipe where the secondary catalysts are (just behind the gearbox) – there is a separate pipe linking both banks of cylinders. The owner of exhaustsuk said that the linking pipe at the secondary cats meant that X pipe was not needed to replace the center silencer (which had an AMG stamp on it), as the exhaust system was already ‘balanced’ at the secondary catalysts stage. We could simply fit straight through pipes. You will see from the pics below that the center silencer (under the rear seats) had 2 inlets and 2 outlets. I decided I wanted a X pipe to replicate the effect of the center silencer (except for the silencing!) for more ‘balance’ and hopefully a more even sound. They said that was fine. The center silencer was cut out, and we planned to re use the clamps holding the silencer place. In part this resulted from necessity as the exhaust pipes were not of a diameter pipe that exhaustsuk made or had in stock. I asked for there to be as large a chamber for the X pipe as possible. They thought they could make it from 2 sections of pipe with cutting of pre-made curved pipes and welding. Turns out that they had to make 6 separate bits due to the restricted space and because of the curvature of the slightly curved pipes that they had. I am sure the price quoted did not envisage the extra cost and effort involved in having 6 bits instead of 2, but exhaustsuk honoured the original price without a murmur. Making and fitting The guy who worked on my car, Karl, is a master craftsman. He spent about 3 hours designing, measuring, cutting, fine tuning, welding, polishing and fitting the X pipe. It was an utter pleasure to see him work. It was as if he was working on his own car. The care, the thought, the skill, the intensity, the concentration, the dextrousness, the experience .. it was superb and almost magical. It is wonderful to know that we have these skills available. I told him so, and he said he really enjoyed working on my car, as it was such a challenge and so different to simply attaching pre made sections of exhausts. You can see from the pictures what a top quality job it is. The welds are almost unnoticeable, the design flowing and OEM. The quality really shines through. What does it sound like? In summary, absolutely fantastic. At low speeds in town, there is now a louder, clearer and not at all intrusive V8 burble or hum. The sound depends on how aggressively the throttle is depressed – with the result that it is still very refined when pootling, but significantly more audible when pressing on. At a constant speed, there is virtually no difference to OEM. The refinement has been retained, but the voice is there when and where you want it, at all speeds. At a constant motorway cruise, it sounds exactly like it used to (which is exactly what I wanted), but a bit louder. The difference is that there is more depth, more presence, more clarity, more volume, more thunder and more roar when you play with the accelerator at any speed. It’s the difference between an outdoor concert and a concert at the Royal Festival Hall. No droning, no humming and no unwanted sounds at any speed. It is as good as I wanted and imagined it to be. I am completely delighted with the outcome.