From MY Tax point of view: U should be deriving income from MY based on your role/function as a middle-man/art buyer in MY. Since you are being remunerated for that role to your clients the income earned during your stint in MY shud be taxed here.

The time period of > 182 days only determines whether u shud be taxed as a Tax Resident or not.

Since u have been in MY for more than 6 months, I assume u have been travelling back and forth a few times and did not stay in MY consecutively for the entire 6 months.

If you didn't use any Professional Visit Pass or Employment pass to come in to MY for that 6 months duration, then it will be difficult for IRB to prove on your income derivation activities unless you declared to Immigration that your intention to stay in MY for X no. of days was for work/business purposes.

100% of your fees charged to your customers will be paid to your sole prop in SG?

Regardless of whether you are a citizen or not, ultimately your taxes in MY depends on how long a period you were working and deriving your income from MY (> or < 182 days to determine tax rate based on tax residency), regardless of where you are paid and who is your employer or where your entity is officially registered or where the contracts were entered into.

You should mainly be taxed in MY, since you have established a precedence of working mainly in MY. Your passport entries and other business documents and emails should be able to demonstrate this clearly.

Cost for hiring freelancers is a cost to your business, doesn't change the fact on where you must be taxed in the end.

The only thing you need to be mindful of is whether in the past 2-3 years you have been declaring your taxes in MY as nil and declaring your taxes in SG with income. A sudden change in tax declarations would prompt/highlight to the tax authorities on your tax file(s). You must have ready on hand all the necessary documents to justify your basis for tax for both countries.

E.g
In MY: 2014 - nil tax, 2015 - tax at say 20%, 2016 - nil tax
In SG: 2014 - tax at say 15%, 2015 - nil tax, 2016 - tax at 15%

If you have been declaring your taxes in MY all this while with none in SG then no issue. Key thing is consistency. If you aren't consistent as per the above example, then you must be able to back it up with the relevant supporting.