Right about 30 seconds in heating up and it tings/pops once as cooling off for about 10-15 mins after shutting down the engine about 7-10 every min or so. I know it a exhaust sound up front cats or manifold . Just trying to see if anyone has heard this before?

My truck has never done this in the last 60,000 its a 07 4.6 its SCT programmed by VMP and has a Roush off road cat back since 6 weeks after new . The truck runs perfectly fine as it always has and no codes . I am thinking about hi flow cats or shorty header might fix this ?

Thanks for any help.