1- Get the suspension work done before you start worrying about speed.
2- Get it tuned from Honda Pitstop or Fort (the fort ones have a 2000 rupees deal which includes tuning, alignment, balancing and one more thing I'm forgetting-in short, its totally worth it) - you can ask them for a list of everything that needs to be done.
If you feel that the car is working perfectly on petrol, then just visit Allah Hoo computerized CNG tuning. Just make sure he DOES NOT touch your throttle body, infact, make sure he doesn't touch anything except the CNG kit. He'll charge 250, and adjust your CNG settings.
If you want an even cheaper solution, just visit Butt CNG on Bahawalpur road (its the road which connects Muzang to Choburji). Tell him to adjust CNG, he works on his intuition and experience, and 90 percent of the times, it is 100 percent correct. It'll take 2 minutes, give him 50-100 rupees before leaving. He makes most of his money by fitting CNG kits in cars.