Originally Posted by o1roadkingrider

Could be a camshaft or other valve timing component wear. Is the smoke really gray, or is it kinda blue? Could be oil fouling of your plugs if its blue. A fouled plug would cause unburnt fuel in your exhaust, which is ignited by the next properly firing cylinder to create the "pretty loud" backfire.

Check your spark plugs and see how they look. Also, a compression check and vacuum reading would help determine if the engine is working properly before blaming it on a boost issue.

That's my .02 anyway.

JJ