Best way to test performance

[Sparkrite]

My federal TCS is running quite well now. A 220 mile drive last weekend which went without issue. Although Im wondering if there is more performance on tap. Without going on a dyno or rolling road, what are the best performance road tests to try, ie zero to sixty,or say 40mph to 60mph in 5th gear, and what times can I expect to achieve with a stock car but with a big valve head and twin weber 40s.

[Clifton]

https://dragymotorsports.com/products/dragy-gps-performance-box

[Pfreen]

I have used perfexpert for an iphone.  Getting the mount stable is the challenge, but it is interesting, using the iphone sensors to measure hp.
There are other apps apparently that do the same as perfexpert.  It was much cheaper than what clifton posted, but getting consistent results is a challenging so it could be the iphone sensors.