'92 5.0L Speed Density EFI.

If I were to swap my stock exhaust manifolds for shorty headers (Pacesetter "direct fit" units), would I have any issues with the EFI? Should I expect any performance gains?

MAF conversion wouldn't have any issues, but I'm not there yet.

 

Headers will be fine with speed density.

 

No problems what so ever, expect only minimal gains from shorties.

 

If you want more performance gains , you will be better with the long tubes , there worth the exta work ...Lew

 

Agreed. Long tubes are superior to shorts. Being I have a 4wd, I'm leaning toward equal length shorties in an effort to not overcrowd the undercarriage with collectors and such. If it were a 2wd, there would be no question, I'd go long.

Besides, the pothole state of NJ is rather funny with their emissions inspections. I've heard tale of inspectors failing modified cars due to non-stock equipment, even if the system passes the sniffer tests. Shorties will allow the cats to remain in their stock locations. Other than an inspection of the manifolds, the system will look stock.

Good to know that long tubes and SD shouldn't fight each other. I remember hearing horror stories of mods and SD systems involving expensive and sometimes custom chips to correct simple problems. MAF got past all of that.

How far can a SD engine be modified before problems arise? I'm considering a MAF conversion, so this may be a moot question.

 

The gains from equal length shorties over unequal length is also minimal so i suggest you save yourself the headache that they cause with spark plugs and wires and just get the unequal length version. Can't say I have ever seen equal length shorties for trucks anyway, and FYI.. mustang shorties will not for a truck.. the header collectors are positioned differently.
To get the gains from these headers you will also need a Y pipe and cat.. the stock pieces are the cork in the system, but given your state emissions requirements you will want a system that at least looks stock, and the Magnaflow, Catco, and Bassini Y pipes with integrated cats are.

The Ford SD EFI system relies on manifold vacuum to determine engine fueling so as long as you don't upset that it will be OK. That means you can do pretty much anything you want but when it comes to changing the cam you have to be very careful. The 5.0 induction system(intake manifold/airbox/plumbing) is already plenty big for the motor so there's not much to be gained on that side so the best gains will be realized with exhaust work to start, and then the next best upgrade on this vintage motor is a cam change to the '94+ truck cam. You can further enhance that by adding 1.7 roller rockers, and all this will keep the EFI system happy and not increase emissions but also provide more power... especially once the exhaust has been upgraded.