How much of a gain in horsepower and fuel mileage should be expected over the stock filter box. Also, where do I find the prefilter that fits over the BHAF. Thanks

 

The BHAF will give no gain in power or mileage over the stock air box. The stock air box is good to over 500 hp when the rubber fender boot is removed.

 

I just installed the BHAF the other day and have not yet had the chance to run a tank of fuel through it to see if it helps mileage at all. The only real difference that I see so far is that it might help throttle response a small amount and if you have your silencer ring taken out it will make your turbo considerablly louder and allows it to spool earlier in the rpm range. The pre-filter can be ordered from www.outerwears.com and the part # is wr-3325-105.