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Message: [QUOTE="Strictly Diesel, post: 522721, member: 1411"] Short answer, it doesn't work that way. If it only made 20hp more, that's all the power that was left on the table from the use of the stock turbocharger. The gains are probably a combination of a bit more air to finish using whatever fuel might have been left over and the benefits of improved boost:backpressure ratio. Of course, this may open up the window for more usable fuel, if the tuning and injectors are not already maxed out. It's all together possible that it would have picked up the same 20hp at a lower boost level, which would yield less stress on the turbo (stock thrust bearing wasn't designed for that much boost), even less actual backpressure and less heat from the compressor. If this compressor is this efficient, it would be interesting to see what the "before" MAT was, what the "after" MAT was, and then turn the boost pressure down via wastegate adjustment to find where the power drops and test again to see what the the new boost, backpressure and MAT figures (which would require testing with a stock turbo again). If it were mine, I'd try to run it at the lowest boost pressure possible to make the power rather than shoot for the highest boost number with no regard for backpressure and temps. That said, I will try to capture some of this when I test the 38R version. Bob and I have been talking about this for a while now, just waiting to get one to test. I don't have a dyno to use, but I do have a 25 mile commute with sections of highway driving that are never interrupted (next to no traffic). I will do before and after logging of the exact same drive (log start/stop locations), at various speeds (cruise control managed) and various loads (with and without trailer). I've got no problem making my 38R surge with my 200/200s, so we can test that too. Hey Bill...if you're going to do another test, put one of Bobs easily adjustable wastegate actuators on the stock turbo first. It would be interesting to find the peak HP boost/backpressure/MAT number with the stock combination and then do the compressor wheel switch. See what that same wastegate configuration yields with the new wheel (more boost with no other changes like the first test you did hopefully), then adjust up and down with the new wheel to document the BP/MAT at the same boost as the "stock" turbo as well as the boost/BP/MAT of the peak hp adjustment (the point where power stops increasing). Hopefully that made sense... [/QUOTE]