No, not just the turbo, the whole gig - headers, plumbing, BOV, WG and turbo. You mentioned earlier that you know carbs, so you must be able to modify the carb to become a blow through - blow through implies no intercooler needed.
Personally, I can't man handle the carb, but I've considered buying a CSU for $800. But at less than 10 psi, a stock Edelbrock, Rochester 2 barrel or small Holley is easy to handle a small amount of boost.
To answer the question of how much power can you add? 9 psi will add more than 50% of the original power. So a 180 HP motor will make about 270. But here's the deal, once you get the additional 90 hp and can tune the carb to keep it together, then another 15 psi on top of the 9 or so will start yielding crazy numbers. And the only thing needed will be a WG spring.
Personally, I wouldn't dick around with anything other than a set of headers for an additional 20hp. Please don't take my comments the wrong way, I'm not trying to pee on your party here, but YIKES, are you headed down a rabbit hole that leads to a ses pool. Look at it this way, there a bunches of guys making 300hp with an inline 250 from late 60'sand early 70's with psi of boost - everything stock other than adding a 2 barrel Holley or Rochester carb.
Reinventing the wheel is great thing................................................just kidding lol. Kidding aside, I'll repeat, if you can handle the carb work, then build a blow through. If you would like a list of parts for a mild build, then let me know and I'll post links to the parts.
