Not that much heavier.
Enough heavier at what? 40+ Kgs?
And forward of the driveline, not back as the 16v is...not good.
And carried high up towards the head area...not good.
There are reasons why VR6s are harder to get to handle well, comared to 16vs!
You can make a VR6 handle...but it will always understeer more than a 16v on the road...and it will involve more work and more cost to get it close to a 16v.