Because the only hx40 you want will have a bolt on exhaust housing, 16cmwg or maybe a 18cmwg, a v-band compressor housing outlet, then as far as the compressor wheel, the most preferable is the 6 blade 60mm wheel. Usually they are the 8 blade 58mm wheel. The ones sold on ebay are never, well never say never, but 99.9 percent of the time are not the bolt on hx40 with 16cmwg housing 6 blade comp wheel. They're sold on ebay for a reason, the seller knows it's a turd, knows it needs an adaptor to bolt on, knows it's a lag pig, and knows not everyone knows anything about them. Like the hx35, the hx40 has a ton of variations. Most not desireable. All this said, the hx40 isn't that great for hard driving, big horsepower. Some would say it's a hand grenade over 40psi. That said, I would want the best one I could get, not a 'slight play in/out', 'minimal play side to side hx40'.
I'm pretty good at taking a sh$$ on many 'ebay, craigslist, link to ad's'
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