Even harder ones are Hobao's grey truggy springs.
lutach what springs are you using on BPP Truggy? Id need abit harder springs for my truggy and have hard time finding harder ones.
I'm using the ones from Reckward Tuning for the HB Lightning Stadium, but they are really extra hard. The extra hard ones I got for my MBX5T are much softer and I went back to the red Mugen ones.