It is more a question of efficiency, the blower might be able to hit 24 lbs on the boost gauge but the Air Charge Temperature may be sky high meaning you have to pull a bunch of timing to tolerate that boost level. The right sized blower will be able to move the same amount of air without the excessive heating.
^This. As air gets hotter it becomes less dense. The M90 is a prime example of this. Many people have pushed the M90 far beyond it's efficiency range, and it shows in their dyno's and E/T's. The marginal increases you get for every step smaller pulley is a great example how the battle for cooler compressed air starts with the size of your blower per your power goals. There are ways to fight hot air, but ultimately what's coming out of the compression side of the blower is what matters, even E85 won't change that. However, E85 will help you survive it. My Mustang never had issues smashing on M90 cars making equal boost. At 7psi my D1 wasn't even breaking a sweat, never saw IAT's higher than 138 during the summer months (I also didn't try to heat soak it, either). Winter was just beast-mode. And I made a slew more torque than the M90 cars. But it's really like comparing a grape to an apple.
The point is, small blowers are great for small power goals. Trying to squeeze 500whp out of an M90 is just retarded and begging for detonation, and kudos for the guys who do it, not knockin ya but a straight TVS swap and you could run 500whp and barely get the above ambient, not to mention make a fucking fat torque curve. Gonna spend half the TVS money on cooling mods to get the M90 up there... for one good run and then break out the 20lb ice bags and fire extinguishers! lol I kid, I kid..
When my friend and I did a blower swap on his '03 Cobra he said his power goal was 550whp, and he wanted to steggy the eaton and go smaller pulley. I said sure, it'll make 550whp once, on a cold night, with god smiling down on it, and an angel behind the wheel. So the next week he shows me his shopping cart from Lethal Performance with twin fuel pump hat, fuel line upgrade, twin fpdm's, blower pulley change kit, and a VMP 2.3 TVS kit. I was like, really? You sure you want to go balls out like that? He says, it won't even phase my bank account. I said, well let me make a minor adjustment to your order then. Grab the laptop, delete, delete, and add. He says, WTF do I want a 2.9 Whipple for? I only want 550whp. I said, #1 banshee scream, #2 it'll make 550whp, #3 you got an extra $800, and #4 the 3.4 Whipple won't clear the stock hood. 4 months later, his car is screaming along on the Dyno @ Dynojet Labs to the tune of 630whp/595wtq @16psi (running the big ass pulley that came installed on the blower), 128 degree IAT's on a 90-95 degree Vegas day. On shitty 91 octane. With a DA of 3300 feet. On a Dynojet Labs heartbreaker dyno. SAE. We were eating twinkies.
I know I know, cool story bro. But I was there.
