I currently have a auto swapped c6z with a 6l80e bought it this way. I absolutely love the auto in it but it's going out meaning its shifting really hard.

Since im into drag racing I thought about swapping to a rpm 4l65e. Is this a good swap? How much lighter is the 4l65e than the 6l80e? Rpm transmission said the 4l65e is better for drag racing and race proven motors sports said the same thing. I had 2 other shops say keep the 6l80e but I have honestly not seen a 6l80e faster than the 4l65e from the research I have done with identical hp.

I currently make 593 rwhp on a mustang dyno through the 6l80e the car hauls ***.

 

The 4L60E (Of the family 4L60, 4L60E, 4L65E, 4L70E, and 4L75E) would work fine.
I do not see it as a big improvement necessarily over the 6L80E/ 6L90E transmission.

At your power level, you would be far better off going to the 4L80E/ 4L85E transmission (if it will fit without significant modifications).
The 4L60E could support a good 1,000 HP at the wheels... but the unit becomes stupid expensive to build it to that level.
The 4L80E would be far more cost effective... and stronger.

The 6L80E could be built up with aftermarket parts to support your power level and last a good while.
The place where the 6L80E would be lacking, is in shift quality when compared to either the 4L60E or 4L80E.

I would only go to the 4L60E if the 4L80E swap proves to be problematic.

 

you need to chime in over on the CF and ask subfloorcenturytrans he has a built A6 with similar power as yours running 9s in the 1/4 and races alot the A6 can be built to hold alot more power but it has to be done by the right shop