I have Comptech on 06 TSX 5-AT.
Engine mod is only Injen Intake and Exhaust. OEM Header, OEM ECU, OEM cat.

at times, i use tiptronic, it makes a wierd "tiny exploding" sound.
it's not dramatic, but it makes this backfiring sort of sound.

I am not extremely high revving in this case at all.
This sounds can be heard when i am shifting 1 to 2nd.
car is going smooth, i rev 1st gear upto about 3000~3500RPM and smoothly shift to 2nd, i let gas pedal go a bit (just a bit to feel a little lump in acceleration off the car) and when i push gas pedal (not abrubtly) it sounds like some high pressure gas that's been occupied being fused out or exploding.

I am pretty sure this is due to Injen SR intake or Comptech SS exhaust, especially the Comptech SS Exhaust is very deep tone.

Any ideas?

 

Where does it seem to be coming from if you can tell (front, back, either side)?

 

from the back exhaust, but it sounds like it starts from half end of the car

 

Thread bump! I have this issue and I am curious. Same symptoms except I took off my exhaust, test pipe and headers and went back to stock. Just started happening 6-7 months later. Feels and sounds like it comes from the center of the car. Any else experience this issue? I have a 2004 6spd with 135k miles.