Traditional 401k vs Roth 401k

[Phi Tran]

Hello everyone, I am very new to this forum and excited to learn. I have a simple question to ask, and realize the answer may be to speak directly with a mortgage lender, however I am wondering if anyone knows first hand what the answer may be. 

My wife and I own a small business and after the end of this year we will have 2 years worth of income. The first year our net income was $160,000 and this year we plan to make about $230,000. 

Our CPA is encouraging us to contribute max to our Traditional 401k, however I am wondering because this is a pre-tax deduction will this affect our "buying power"/mortgage amount in the future? Would it be better to contribute to a Roth 401k? 

Recently I was told that when applying for a loan, only our net income is considered and not our retirement contributions, is this true?

2023 Plan: Acquire a multifamily property to house hack. 

Thank you!