Raceworks Aluminium Fabrication Donut Welded Outside OnlyRaceworks Aluminium Donut. Welded outside only. Raceworks have introduced a new range of high quality aluminium tube. Made from 6061 grade Aluminium, our tube is suitable for all forms of intake including aspirated, turbocharged and supercharged applications. In some drag racing only applications, Aluminium Tube is also used for exhaust. Aluminium Tube is much lighter that steel or stainless steel pipes, and offer excellent corrosion resistance.