As these cars get older and access to the coils/plugs/upper catalytic converter/O2 sensor etc...is necessitated more frequently I replaced (6) of the plastic clips for the upper cowl cover. The clips inevitably break upon prying (there are still (3) needed for the smaller section as I could not make the mod and drill thru and/or align the new screws/bolts with their respective clip locations). The metal panel under is bolted in, as is (not clips) and is easy to remove, to further gain access to behind the engine, yet the upper cover has always been a bit of a PIA to reseat. I used 5/16 inch x 1 inch long Home Depot (no affiliation) black deck hex head lag screws to good end. I drill a pilot hole thru the plastic from behind for each of the (6 in a row) locations, (starting from the windshield wiper motor side) and then switched out to a larger drill bit (5/16 inch) to enlarge the holes to fit the shaft of the lag bolt (looks like a big sheet metal screw with a bolt head). Then installed new plastic clips in the short section of the cowl cover and laid in the long piece with the (6) new anchors. One inch is just long enough and don't torque the bolts down much or the threads will skip in the body slots/openings; just beyond finger tight is all that seems to be needed, no washers involved.
I did not do the mod to the (2) hinge covers (1 clip each) as 5/16" threads were too big for their clip hole but I will probably do the same type mod with a larger (3/8"?) 1 1/2" long screw at the clip location.
Hope this helps somebody else. P.S. While on improving access- I often use a (3 foot?) bungee chord instead of the factory hood prop to lift the hood farther out/up, making a lot more head room, hooking into an existing hole under the hood and hooking the other end into the passenger side window channel rubber [gotta roll down the window some]. Just don't over-extend the hood.
Huff 2009 (bought new) Fit/Man Trans

 

I accessed the smaller cowl covers enough that one is currently being held together with hot glue!
Next time I change the oil I plan on tightening the sparkplugs and finally replacing them: