The Chinese 90mm fans are a very mixed bag when it comes to efficiency and performance. The JP and EPF fans are about the best of the Chinese (EPF better) but you are wasting $$ on bling that you will never see and sacrificing performance. Models like the FlyFly Sabres, Hawk, and especially MIG15 do best with fans that work well in long often restricted ducting. The Wemotec EVO or Jetfan (both made in the EU) are superior performing products that are also lighter than the Chinese alloy fans.
You will never see 10lb of thrust from an EPF 6 cell fan, you might see 3.5-3.8kg on the bench but look at the amp draw, 120A/2600+ watts, that's a real hard hit on a 5000mah pack. An equivalent custom Jetfan that I build will produce 3.6kg thrust all day long on 6 cells, and 4.5kg on 8 cells, its lighter than a JP fan and has superior dynamic thrust in the air to the Chinese fans. The
EXTREME GRP Jetfan 6s pulls 2300 watts and puts out 3.6kg thrust in the standardized bench testing with inlet lip. The
EXTREME GRP Jetfan 8s pulls just under 3000w to produce 4.5kg thrust on the bench. In comparison the JP 8s fan pulls 2890w in their video yet only manages 3.9kg thrust. The
Wemo EVO does similar figures to the Jetfan and has a slightly different sound. EVO & Jetfan are about the lightest hi performance setup you can get.
Retracts, I did a kit for retracts as I was the original importer for FlyFly and HTG in Australia. You wont find HTG anymore as Ricky Wu ran off closing the company and owing $$ to people including me. Mandy who was his partner and still runs FlyFly is a good person to deal with, she has unfortunately stopped shooting the molds for the F4 and F100, she is still making the Hawk, F86, Mirage 2000. I believe she still has Hunter kits in stock.
if you are interested in retracts for your F100 you can go to my
90mm FLYFLY page and find retracts and struts that I put together especially for these models. The factory struts are pretty average, my struts are a lot stronger and better looking with better wheels. Bear in mind pricing is in AUD, so for USD multiply the prices by 0.75.