[s-cars] Unusual noises???

[Robert Myers]

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Hi Y'all,

The car:  1995.5 urS6 w/ rs2 mods, MRC s/w, 034 RS2 replica 
injectors, 1.8t coil mod, large FMIC, Stromung exhaust sans kitty, 
plus a bunch of other goodies.

The noises:  a popping exhaust sound reminiscent of some of the 
sounds I used to hear back in the fifties from hotrods with 
aggressive cams.  It happens only when letting off after being into 
decent boost and then only once or twice for that let-off.

What I think may be happening:  MRC s/w goes rather rich at WOT and 
when letting off a little "excess" fuel is dumped into the exhaust 
where it burns with a "whump" when it doesn't encounter a kitty.

I plan to check compression but haven't had time to do it yet.  The 
engine pulls strongly and boost peaks to 27 or even 28 psig under 
"ideal conditions".

Does my diagnosis pro tempore sound feasible?

Bob