headers ....is too open....good headers will always make more power..
i prefer dynomax straight thru welded mufflers myself...as they have proven the best bang for the buck on almost everything i have ever worked on.
i preferred the flo pros over the flomasters for cost verse abuse they will take for off road rigs....if you like to trail ride and drag your chassis on stuff...they made more sense...
on your mustang...not knowing your actual HCI scenario.... i would wager if you threw away the turbo mufflers and the glass packs and ran offset dynomax straight thru mufflers you would have ran 13.20 or better with some tuning and maybe cracked 12,s if there was enough timing left in that cam scenario...unless that is what you are calling turbo mufflers. the actual turbo mufflers i have seen are garbage....from the 70's 80's and 90's...but they sounded cool. i assume these are what you had.
i would need more data. heads actual, cam actual, and intake actual,....the intake and exhaust side and valve events will dictate ideal pulse flow. even then....you need to play with the actual exhaust to get the best numbers. in theory no exhaust makes the most power...but thats not always the case as the power pulse
in unioned with the power pulse
out is the key factor...
we have built many N/A engines that exceed 100 percent v/e and some 116 percent volumetric efficiency....moving the exhaust x pipe point 3 inches or the muffler 3 inches affected that.....wildly.
generally the relationship from a flow rate, flow velocity, and pipe diameter is a well used formula. i could be wrong.....but i seem to remember as a constant...two 2 inch id pipes will out flow one 2.5 inch pipe....in velocity....but not even close to a 3 inch. it was very touchy and almost an exponant....
when you move up from there is gets more radical. the 3 inch was good for over 400 hp and a 3.5 600. two 2 inch would seem to equal a 4 inch just looking at it to the average cave pig, but its not even close....but they will outflow a single 2.5 on the math iirc. regardless it is simply not the whole story.... actual construction is key overall.
there is indeed a case... and like you, i would argue the general outcome where a single 2.5 all things being equal, will definitely out
power-curve and outrun two 2 inch pipes.. based on a 300 hp engine. happens every day. even know the cross sectional math says the two 2 inch pipes have more flow capacity.
and this is the case for a typical explorer swap into a sla chassis ranger. there is 80 horsepower locked up in the cam and valvetrain and exhaust of that engine. and these exhaust manifolds can handle that. like what i suspect you allude to...it will quiet the underhood noise, and for a daily driver bolt in swap i would cera-kote them and move on.
of course it would all have to be free if i were working on a ttb chassis....because i would never spend money on that over swapping in a LS platform where for usually a third to half the cost i get a 100 more hp and the same or better fuel economy.
i started putting v8s in rangers in the 80's and for a gen one and even a sla, adding a u joint is a given.... but for different goals and reasons.
in the mid 90s i built...and help build 3 trucks at the same time one of them mine.... two were efi gt40 302 and one was a carb ho 351.
the only difference initially between the 302 trucks was body lift and exhaust. the single 3 inch exhaust would blow the tires off from a dead stop....my true dual 2.5 in exhaust would not....my best was a 14.20 and the single was able to crack 13's .... on the hiway i could pull from a 60 roll no problem....from a dead dig i was screwed. very illuminating. efi was still not a common swap but i was seasoned by then(1995) but...even to this day, while i do tune....i am not a true tuner of it...i had alot of help though for the time period back then.
we started out with the long tubes of course due to the type of engines which were high performance at the time....and the swap "kits". the typical flat flange gasket garbage headers and "turbo mufflers" or flomaster crap.... biggest issue with restrictive exhaust is heat under load. so if your using the truck hard doing truck stuff.... heat rejection becomes a issue. especially driving 2-4 hours a day one way... the engine makes much more heat..... and if you have headers...this is really apparent...i learned alot of shit the hard way....i did not like electric fans and refused to use them initially....but i loved efi for offroading...i was trying to force what i thought was best to work....eventually i let the dyno, mpg and temperatures and parts replacement decide what worked for the application.
my chassis has been through all of those iterations.
View attachment 104325View attachment 104326View attachment 104327
those 351 cobra R headers work really well and were made under a different number for some time....which i found out recently.
but k code stuff is much better then granada and will accommodate p heads....
to me its the simple option unless your going for over 380 wheel.
i was hoping to find pics of redirect for sla but so far not.....these pics i found trying to get some together for the ugly truck thing....
at the end of the day...screw those obx headers if your just wanting to go....get the k codes and make em fit or the normal shorty ranger headers and redirect the steering.
get out and drive what you have.
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