Does removing whole house trap fix bubbling?

We live in a 100 year old farmhouse.
When you flush the 2nd floor new low flow toilet
It makes the toilet on the 1 floor bubble and splash.
My plumber recommends cutting out the whole house trap
That goes to the city sewer lines, there by releasing the
Trap's preasure resistance to the quick sudden 1.6 gallon flush.
We never had this problem with our old 6-8 gallon flushers.
I've put a garden hose down the roof vents, no blockages with them.
No other plumbing issues other than the downstairs toilet burping up
Air bubbles/water spash that will get you wet if sitting on.
Errrgh.

Bubbles indicate a back pressure that's usually caused by a partial blockage. A running trap, (see image ) could conceivably cause back pressure and that's where I'd start. Let me know if doesn't work and we'll explore other possibilities. Good luck, Tom