I'll clarify that purple5ive. Hayley made around 270rwkw with a sidemount & so did another in VIC (I call him Stifler - forget his boardname as he doesn't post often - Tony) with a GT3040 made 280rwkw. The difference is, they did ONE run @ that power, heatsoak near death, wait 30min then do another run & wait another 30min. Not ideal @ all & pretty annoying when tuning. Same thing happens even when tuning over 16psi 200rwkw on smaller turbos. Anyone that can monitor intake temps will see just how poor sidemounts are. On the road, they're certainly robbed of power via intake temps, which is why I always recommend going further than a sidemount if you can, although understand cost is often a restriction. At the very least, get an aftermarket fan & rewire it. For a bit of perspective, on the past few evenings, in about 10 C temps, after multiple back to back bursts @ 18-20psi, I never went over 38 C. When I had a sidemount, I'd already be over that after warm up & before going WOT.
It's not rocket science, the sheer fact that factory sidemount location is so close to the dump pipe/hotside should really speak for itself. It's the main reason why I disagreed with Rob using sidemount heat exchangers. As he's seen from his results, he was better off with a single front mounted heat exchanger. Don't want to be mean to Rob, but the whole "unique" setup was always destined to underachieve compared to a front mount H/E. The question in my mind was always by how much. If there's no real on road temp issues, might aswell just leave it as it. Otherwise will end up with as many heat exchangers as a W16 Veyron & water lines all over the place.....lol