ah yuo may find out that the fuel pump doesnt struggle. there are heaps of guys on here with 2ndary fuel filters. i ahve one on my 2.5l d22. and there is a thread somewhere about the d40 guys. Stanadyne 100Series are ebing sold by Terrain Tamer with all the fitting gear. you will need to purchase the extra mounting bracket that has been psecially deisgned for the d40.
goodluck
Rusty