Noise during acceleration on 2003 Subaru Baja

Automatic trans - no aftermarket parts no turbo - During normal and/or hard acceleration @ around 2500rpm and not during a transmission shift change a noise that sounds life 2 short bursts of air pfft pfft happen and cannot duplicate when in park or neutral.

no trouble codes @ shop

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1 answer
Could it be exhaust related. Either a crack in the exhaust (seen them crack at the flange at cylinder head, also seen heat shields cause a noise. Check the air filter is installed correctly.