I would suggest you select a blower that matches your other mods and your intended driving/racing style.
If you like instant grunt, then a twin screw or roots style is the way to go. However, with your 4.10 gears, you will have so much instant grunt that you're always going to be lighting up the tires.
If you like a car that can launch without a bunch of fuss (or wheelspin), but pulls harder and harder as you approach redline, then a centrifugal blower or a turbo is the way to go.
Like you, I already had 4.10 gears before I started shopping for a blower. Plus, I had a big stall converter which puts me into high revs at launch, so I didn't want a blower that worked best at low rpm's as I'm never in that rev range. That narrowed it down to centrifugals and turbos for my particular combination. Turbos were too much money for this working guy on a budget, so I ended up buying a
Vortech V-2 VQ standard S-trim (non-intercooled) for just $3700. For that price, I got the blower, all install hardware, 39# injectors, 2nd fuel pump, and handheld tuner with basic supercharger tune. Paid $900 for install, and I've got about $400 in custom dyno tuning done. So grand total, part, labor, tax, tune, etc. was $5,000. With a safe conservative tune, and measured on a Mustang chassis dyno, my otherwise 100% stock engine/exhaust is putting down 351 rwhp (about 440 hp at the crank). I suspect a Dynojet dyno would report closer to 380-390 rwhp (about 480 hp at the crank). That's a lot of bang for the buck for the low cost. Other blower kits can provide bigger numbers, but also cost a lot more, so you get what you pay for.
