The P5 is an on-road engine (S1 stamped on the crankcase), ported to suit off-road. Being an on-road engine, it is a long stoke. Therefore, the torque curve is more gradual (less bottom end). If it were a short stroke, it would have more bottom end. But, the top end in both short stroke and long stroke is similar. The only difference is how they get there.
I have a CLB long stroke Nova Rossi, which I modified after testing by Nova Rossi and European driver Daniel Vega showed more power and better fuel economy by 1. changing to a larger (on-road) head and turbo button; 2. 25% nitro, 9% oil, 66% methanol & also using the 9886 on-road pipe. These long stroke engines are suited to tracks with less grip as the power comes on more gradually then the short strokes that give you instant power & torque.
The P5 is essentially the CLB modified as above, just reconfigured and sold by Nova Rossi. I know this as I also have a P5. So, if you want more bottom end buy a short stroke eg. SBK and run a 9853 Nova Rossi pipe (good in high grip situations), for slippery tracks run the P5 with 9886 pipe. Give it a go. Let me know. It works Down Under.