Now I "try" to fill the tyre wake. If I run it all the way to back to the car pipe would weight at least 3 kg more, have 4 tight bends more and I dont think I can afford that with my weigth saving target. That is true with current setup it will inrease the drag little bit but I will make it covered so that it will not be in the airstream. Maybe even more extreme version through the hood will come in the later phase. That would only weight 2 kg
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For the illegal part it is allowed to have side exhaust on the left side like I have. Its illegal on the right side or it has more limitations there. Exhaust tip needs to have 50 mm clearance to body which I have. Noise limit is 85 dB and I believe its under that by clear margin. That is at least my knowledge on the subject. Of course the police have their own opinion on the subject, but the noises arent so bad IMO.
My Lupo was missing the stock engine bellypan.