While using the IT audit to justify additional resources is important you have to bear in mind that some of the findings may not be to IS management's liking.

The key things that you really should be focussing is the "IT Value for Money" question.

Generally value comes from the two key roles of IT:
a) Investing for Advantage - Creating Economic Value e.g. If investments are made in the wrong initiatives then economic value may be destroyed.

b) Keeping the lights on - Running the systems e.g. If the lights are not on, then the business will incur extra cost, customer service is reduced, IT user staff become unproductive and management are not able to make rapid decisions.

Where IT auditors can help significantly is addressing the above two areas which generally aim to improve performance and bottom line profitability.

If you look at a) then the introduction of new/amended systems may help with supporting process change and improving business performance.
Auditors whether internal or external (generally they will have access to a wider knowledge base and experience of process benchmarking, etc) could bring new perspectives and hopefully specific recommendations (pragmatic also) that have been discussed with management. Point b) should seek to reduce IT costs and improve IT services to internal and external customers through IT benchmarking or using TCO to measure performance as we all know there are always areas where we could be performing better. If you can show business management that you are identified savings along the line they are more likely to provide you with the cash to help improve the current ways of working (even in a though climate).