The exhaust is 4'' x 14''..

My budget has been pretty tight due to unexpected medical bills, that's the only reason I was hoping to make due with a 4" filtration system. That's a solid suggestion though and I may be able to cut some corners elsewhere to make that work.

If you want cheap https://www.amazon.com/iPower-Inch-195-Inline-Circulation/dp/B09B21W4C6/ref=pd_ci_mcx_mh_mcx_views_0?pd_rd_w=C0fJC&content-id=amzn1.sym.1bcf206d-941a-4dd9-9560-bdaa3c824953&pf_rd_p=1bcf206d-941a-4dd9-9560-bdaa3c824953&pf_rd_r=WH8SRDAEDQRW6PHTXC9V&pd_rd_wg=841f4&pd_rd_r=09100abb-2e2c-44bb-9505-6893e9a96d66&pd_rd_i=B09B21W4C6&th=1

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If you want name brand https://www.amazon.com/dp/B06XFRNPR8/ref=ci_mcx_mr_bw_mh_d_sspa_dk_detail_2?psc=1&pf_rd_p=d175b668-34ca-4e00-80df-baa0ace9f518&pf_rd_r=WH8SRDAEDQRW6PHTXC9V&sp_csd=d2lkZ2V0TmFtZT1zcF9odWNfdGhlbWF0aWM&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFDRFNOMVRCWTIyT0omZW5jcnlwdGVkSWQ9QTAyMjk0MDNWU1JHTEJRVjdZSDcmZW5jcnlwdGVkQWRJZD1BMDQ3NDQ1NTIwNUZVQ01aOUY0Rlomd2lkZ2V0TmFtZT1zcF9odWNfdGhlbWF0aWMmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl