For FICO 8 scoring models, you will get a bump in scores with a mature (24+ months) loan that is paid down significantly. Once the loan is paid off, your scores will drop to what they were before the loan.
With the previous scoring model, installment loans are pretty much ignored if you have at least 1 credit card reporting.
You can build a credit score over 800 with credit cards alone. I wouldn't waste time or money on an installment loan unless you actually need the loan, and if you already have a mortgage reporting, this won't help you anyway.
Thanks, pretty sure you were the OP I saw talking about this. Appreciate the advice!
Regarding 'few cards reporting a balance' how much does this impact score? I rotate through unused cards every 3-4 months but will put $10-20 on each, so this should be spaced out?