I am in the need for a new subwoofer

I have m80's with a vp 150 center I think the ep 350 would be the best match but It is more than I would like to spend

So I am considering the ep 175

Will the ep 175 match with the m80's and will it be okay in a 15x18 room

The decision on which sub you choose in part, depends on what you are expecting from it. If you want deep bass found in some types of music, LFE for movies ect, I would be looking at an EP350 or bigger. I don't think the 175 would make a very noticeable difference with the M80s, which already have pretty good bass themselves. The 175 would extend the bottom end some, but nowhere near what the 350 would. Again, it depends what your goal is. Have you considered either the Factory Outlet(FO) or Owner's Club to bring the cost more in line with your budget?

I don't believe the EP175 is made for a room that size.

According to Axiom it is designed for rooms around 12 x 20 x 8, so your room most likely would be ok for the 175, placement is key. As Adrian mentioned, a lot depends on your goal for its use. Since you splurged for the m80's, maybe an EP350 from the Factory Outlet would fit your bill.

I am looking to get more bass for sports & movies

I know the 350 is the way to go I think it will be worth it to spend the extra money

Thanks