Are other games lagging?
What HW version is your router?
What Game console do you have? XB or PS?
What ISP Service do you have? Cable or DSL?
What model ISP Modem do you have? Stand Alone or built in router?
Ensure DNS IP addresses are being filled in under Basic/Internet/Manual?
Turn off Advanced DNS Services if you have this option.
Turn on DNS Relay under Setup/Networking.
Setup DHCP reserved IP addresses for all devices on the router.
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP.
How are you connecting? Wired or Wireless? For gaming it's preferred wired (cat6 or cat5e) however single mode G or N works well for gaming.
What wireless modes are you using?
Try single mode G or N at 2.4Ghz?
What security mode are you using? WEP, WPA or WPA2? Preferred is WPA2.
What wireless devices do you have connected?
Any cordless house phones?
Any other WiFi routers in the area?
And just know that gamefuel and routers can't prevent ALL game lag, as mentioned in the XBL sticky, there will be other circumstances that produce lag.
Let us know. Maybe we can teamviewer.com in and help make sure the router is set up well.