Had envirotest smog my 72 K5 and failed due to high CO, I leaned out the mixture and failed again with high hydrocarbons. I took it to repair shop and they told me they wouldn't work on it because the engine is modified and they wouldn't be able to pass smog(750 cfm edelbrock carb) I feel I am getting dicked around with. How are you getting your blazers to pass smog inspection? Will collector's plates avoid this situation? Thanks in advance for your advice.