I just put some Vortec heads on my 88'K5. I was going to use some Flowtech headers untill I realized that they wouldn't fit my aftermarket exhaust system. So I decided to use my stock exhaust manifolds for the time being. Nope, won't fit. 4 out of 6 bolts fit but the last end port/runner bolt holes are about 1/2 inch off. I asked around and I guess the Vortec's are different. I can't be the only one here with Vortec heads so what are other people doing? Thanks for the help. Displacement, cubes, and did you say you drive a riceburner???