engine swap first road test help with noises

[Grandprixpaul]

At idle the car is humming like a low base note when i give it gas she quiest right up, im thinking I
The exhaust is rubbing up against something just wondering anyone has had this happen.

 

[bigalturk1]

If your exhaust system has a muffler that fits sideways behind the rear-end in front of the gas tank, you will get some noise. The pipe, muffler or hanger may be contacting something solid. I like the Front to rear exhaust systems better.