If you're really starting on the 1/8, what you really dont need is the ultimate slingshot ready for destruct your car at the concrete wall of the backstraight.

Hence, my best bet goes for a Novarrosi RX221 or similar. RX321PS and others may give you excessive speed that you really don't need (for now....). For the price of a JP, you may get a pair of 221's and have one for practice and other for race (keep the practice as backup of the race).

I have some old but really pretty and quick RX21-R1's (Planning to get a 321 for my MRX-3).