Ooh yeah. I could only afford their Stage 2 or 3 Yella Terra red engine head when I was an apprentice but I had an engine engineering mate and we took it to stage 5 cheaply (there's some interesting word juxtaposition in that sentence). Wish I could have afforded the roller rockers in that pic, I would have saved some money in the long term when I turned a noninterference engine into an interference engine with some serious valve bounce issues at 7or8K rpm. I'd used a 202 bottom end and a 186 YT head ported and polished to hell, all well balanced, and triple SUs, but there was a very serious cam grind (the brand escapes me right now, but they were northern NSW, and good), I kept stepping up each rebuild but it ended up way above XU1 spec, a 240kmh missile even just with M21? 4spd gearbox; but yeah I'd gone too deep for my pockets at the time, and ended up basically giving it away when I realised I couldn't be bothered nor afford to fix bits again.
Full disclosure I swapped the beast for a ****ing shitty Toyota Liteace. But that got me out of Lismore, so, uhhhm, yeah. With hindsight, **** I wish I still owned that car. The engine alone would be worth 20K today. The ACL aluminium pistons stood up to dents and it was likely only a bent valve or two as usual.