nothin wrong with the redcat 1/5's.
I had bought a KM baja (hpi clone) and thought it was a great deal....till I raced a guy with a redcat rampage. That rampage smoked my baja in every way!
Now, on to your issue.
These engines are pretty simple overall. You have to look at the problem like if it was a weed wacker or chain saw.
You low-end power is very poor. This sounds like a engine running rich.
You have to have the choke off (once you have the motor started and idling)
You will want to adjust the low speed needle. there are 3 adjustments...the idle, low speed and high speed.
If the buggy is fine once its moving...then the high speed needle should be set right.
If adjusting the low speed needle makes no improvement....then there may be an air leak...
Check the gasket at the car(and the bolts) or check the muffler is on good.
If you buddies were good friends, they would help you diagnose the issue instead of wraggin on you. It sounds like they know 2 stroke motors, so they should be able to find the issue.