One of the turnkey providers I work with is offering 1% a month gross rent multiplier with a tenant and under management.  

Here are the numbers for the property:OverviewMonthly Income: $900.00Monthly Expenses: $961.09Monthly Cash Flow: -$61.09Pro Forma Cap Rate: 3.54% NOI: $2,016.00Total Cash Needed: $16,225.00Cash on Cash ROI: -4.52% Purchase Cap Rate: 3.54%Property Information Purchase Price: $56,900.00 Purchase Closing Costs: $2,000.00 Estimated Repair Costs: $0.00 Total Cost of Project: $58,900.00 After Repair Value $56,900.00Down Payment: $14,225.00 Loan Amount: $42,675.00 Loan Points: $0.00 Loan Fees: $0.00 Amortized Over: 30 years Loan Interest Rate: 5.000% Monthly P&I: $229.09ExpensesVacancy $54.00 (6%) Repairs $90.00 (10%) CapEx $198.00 (22%) Insurance $100.00 (11%) Management $90.00 (10%) P&I $229.09 (25%) Property Taxes $200.00 (22%) Total $961.09 (107%)Financial Projections Total Initial Equity: $14,225.00 Gross Rent Multiplier: 5.27 Income-Expense Ratio (2% Rule): 1.53% 50% Rule Cash Flow Estimates Total Monthly Income: $900.00 x50% for Expenses: $450.00 Monthly Payment/Interest Payment: $229.09 Total Monthly Cashflow using 50% Rule: $220.91

Sorry, no data......from my view:If one earned money from which to "fix-flip"(unless you have a Gen Contractors lic, have side time... whatever), my opinion, [CAUTION] South Florida is nonsense clown act, (synthetic growth), Irma money is overbuilding / lifting a false R/E data market, and thanks to local tax multipliers are up 1-2 points; only adds to "comfort levels" if looking at SOUTH FL,  Monroe/Miami-Dade / Broward , etc, the East coast of the State has no industry to fund usual and customary lease terms.

How is this multiplied to maximum effect?

David Greene talked in one of the most recent podcasts about building wealth, then multiplying it and finally investing it (or something to that extent).

My suggestion is to use that saved money and then try to create another funnel where eventually the investments will keep multiplying on top of themselves.  

This is why I like using GRM (Gross Rent Multiplier) - Cash-on-cash and Cap Rate both depend on calculating your expenses, and the best way to boost those metrics is to calculate your expenses wrong :).

I multiplied the ARV by 75% seller wouldnt go lower than 65k

.- And i guess as a bonus, if you had this cash, what would you do to exponentially multiply it over a 100+ year period?

We tend to target a GRM (Gross Rent Multiplier) of 10 or less, which puts you just under the 1% rule.