Seller Concession on Investment Property

All, I wanted to get some idea with the sellers concession on Investment Property's

Can the Purchase Price + Seller Concession surpass the appraisal? also is there a max limit of 2% for Seller concession on Investment properties?
I am under contract on a duplex, where the appraisal came just $3k shy of the contract price. 

So for example: Contract Price was $130k, the appraisal came at $127k; I think I might be able to get the seller lower the price to $127k to match the appraisal. But can I ask for seller concession to cover some of my closing costs, if so, can that be $127k + $2,540 (2% of $127k) which will be above appraisal. 

Or does the new purchase price plus 2% of Seller Concession need to be max at $127k, which is the appraisal value. 

Thanks

Kunal M.