HaloMods "Classic" Read-only Archive

It wont let me import a model into hmt3 and when i try to it says
error: cant inject problem.
Maximum indices for this model: 1371
your modle has: 1829
If theres anyway to fix this plz tell me. thx

first what program are u using? second make sure when u are modeling that all u are doing is moving verticies around and not deleting or adding anything to the model.