I had all my weight on my car full weight with 3/4 tank of gas I still manage to pull a consistent 15.3 but that elevation probably... I live in houston tx if that helps
I would say keep it and find a front bumper that doesn't have sun damage or restore that one and keep it for longer and I'm sure you'll get more than what your asking for.
So if I work on my 60' I could get a better time because I don't want to mod my car until I start getting at least 15 flat I already got cash saved but I want to see some improvement on my time. Anybody got tips?