Yep. Depends on what year too. They changed the cam just about every year. Some years had a truley horrendous head design (my 87 for example) Fucking things weigh almost 2 tons (t-tops and convertibles) Also depends on if it was an L89 (305) or an LB9 (350) ci engine. You must also remember the suspension on IROCs is completely different as is the cam from regular Z-28s. The cars were not meant for straight line racing they were made for oval road racing and auto-x. If you dont believe me when I come back down Ill take you for a ride in mine. Fucker handles like its on rails. The cam is pure torque and no top end horsepower. However if you are lucky enough to stumble upon an LE1 Z-28 be forewarned...they were lightweight hardtops equipped with a 350 (most 5-speeds) 3.73 rear ends and absolutely 0 options. No A/C no power anything. They were the factory race car.