The Coalition has been urged to simplify the current regime to make it fit for the 21st century by the investment company's chief executive Andy Bell.
Mr Bell put his suggestions to the Financial Secretary to the Treasury Sajid Javid in an open letter.
He said the lifetime allowance and its associated complex protection regimes should be ditched and instead the annual allowance should be used as the primary control on pension tax reliefs.
He wants to see the current capped drawdown pension rules simplified, moving to a simple percentage based regime where an annual income allowance is based on the saver's age.
Mr Bell believes this will provide savers with increased certainty of their likely maximum income based on their pension fund value.
He is also calling for the re-introduction of a simple list of permitted investments for Sipps containing all mainstream quoted investments, UK regulated collective investment schemes and commercial property.
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He said: "This will help to address the number of failing investments made through Sipps and provide investors with greater protection."
Other key recommendations he made include:
• Scrap flexible drawdown and introduce a straightforward more accessible requirement enabling savers to withdraw 10% pa of any pension savings in excess of £200,000 irrespective of their age.
• Apply a single rate of tax of 35% to lump sum death benefits on both uncrystallised and crystallised lump sums.
• Allow a saver's tax-free lump sum to be drawn early but only to people aged 45 and over.
• Extend rules on serious ill health lump sums.

Mr Bell said: "I am more convinced than ever that change is needed to the current system.
"Without a fundamental review, the system will fail to engage many pension savers due to its complexity and lack of flexibility."