Simon,
Hello, my name is Mike Sr. and I'm a cheapskate.
Get yourself a 1-1/2" carbide hole saw and cut it in half. Weld in a piece of the same size tubing between the 2 pieces you just cut. Make it as long as the number of baffles you wish to remove (30" worked for me). If you go slowly (very important!), you can slice thru all the baffles including the offset tubes. Check to see that you are progressing on a straight path frequently. You will leave enough of the baffle to maintain some back pressure and tone it down a bit. Do not use a big, powerful drill! It will knock the teeth off the bit: Better to go slowly with a smaller drill that occasionally stalls.
Worked for me.
