Hi All

I just want to get people's opinion about something.
As you all know I have the A12GX engine.
This past weekend I decided to drive my car slowly in the revs to see what happens where.
all the way to 3500rpm it is nice and smooth.
At 4000rpm it starts to make alot of engine and exhaust noise and a bit of vibrations.
At 4500 it really starts to make noise and more vibrations and at 5000 it makes alot of vibrations.

I was informed that the engine and exhaust noise is normal as the revs increase.
My question is about the vibrations.
How must the vibrations be if the engine is out of balance.
The vibrations is not like asif the front wheels are out of balance and whole front is shaking it is more like when you have a small hammer drill (Not the big heavy duty ones, but one of those that you buy at a hardware store)and you are busy drilling into a wall with the hammer drill. This is the only way I can explain the vibrations.
Is it not the harmonics of the engine?
I would like to balance the engine but this is the maximum revs I will use as we do not have a race track and I mostly will use it on the roads and rev it a bit hard.
I do not want to spend money that I can use for something else, for example buying a 5 speed gearbox .
Can I drive the car like this or will it later give me problems or cause premature wear.