Great success with antenna mod!
 

I just added a telescopic antenna to my tranmitter, and a solid copper antenna to my 27MHz MicroSizer last night. I added 16 feet to my starting range of 6 feet!

I found that a solid core copper wire gave the best results as a car antenna. I found that the small gauge copper wire that is in the middle of cable TV cabling (co-axial cable) is perfect! Strip off all the outer insulation and braided wiring, and you are left with a nice fine copper wire. IMO it looks better on the car with no ugly insulation around it to detract from the car.

It extends about 5 inches above the car, and now my total range with this 27MHz is about 22 - 25 feet indoors!

dam...good range there buddy..i need more range

I have done the same thing and might have gotten enven better range but I ran out of apartment so tonight I will test it out on the campus parking lots when the crowd clears out.

Indoors vs Outside
 

I think you will find that outdoors you have MUCH better range. Has to do with interference I guess, but outside, my car can go 50 feet or more. Inside, it's a totally different story. If you get good range outside, be sure to qualify the numbers with the fact that it was outside.

No crip-cap in any of the controllers I have. Just car and transmitter antenna mod for me.

Yeah I removed the cripple before right after I put the car together.