I recently had an exhaust upgrade to Vance & Hines shotguns . I had a stage one done my EFI engine and it now has a popping noise its not a constant pop but sporadic and increases with speed w hats my problem???

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charlie reynolds

Does it occur on deceleration?

deceleration will be normal but under load something sounds wrong

check the plugs and see how they are burning.

Reference chart: http://www.triumphspitfire.nl/plugs.html

Chances are, you'll need to have it checked out.