How much HP does flowmaster add?

my ghia is white with lots of stock chrome like on the wheel fenders, outline of windows, atenna etc.. so i think chrome rims would look tight on it expecially with the mirror tint.. back to the real subject what about the new super 40 series, on the commercial it said it can add up to 40 hp to your v8.
 
See Mustlecarfan88s comment above. If your current exhaust is causing you to loose 40 hp then that's what your gain will be. If your current exhaust setup is robbing you of 5 hp then that's what your gain will be.
 
for the love of god do not put those spoked chrome wheels on put some chrome cobra r's on it or something if you want chrome :D , 143hp, i didnt know you could get a 5.0 with 143hp im missin out
 
If I read correctly you have a stock 79 Mustang Ghia, with the 140 hp 302, with the stock Motorcraft 2150 2v. Stock it has a single exhaust, with one single stage converter and single tailpipe.

I added headers and duals to my 79 Capri Ghia 5.0 when it was stone stock, and it revved noticably quicker, but still probably not more than 5-10 hp difference at the most.

That car probably has a really tall gear, like a 2.47 or 2.21 to 1 as stock. Changing that to a 3.08 or better will make the most difference in performance feel.
 
I vote for .75HP more but a lot more noise lol. Go for headers, x-pipe, and true duals... you might loose some power in the low end (headers) but gain some in higher revs...

But before exhaust, might want to allow the engine to breath in also.

It's like you're forced to breath in via a 1/16" straw and breath out with no straw... Your lungs won't fill in much and won't get much use of being able to breath out more freely.

I'd get 4v carb, better intake, heads, headers, exhaust work... in that order :)
 
custom89stang said:
a full aftermarket exhaust will add around 10-20hp, 20hp for the more modern 225hp 5.0's and for the older ones more like 10-15hp

I'd say it's the other way around. The more modern 5.0L's came stock with a 2 1/4 h pipe already.....so there's not a TON to gain. But with an older 5.0L a lot of them came stock with single exhaust......there's a lot of potential robbed right there. My 85 GT was a prime example, it came stock headers going into single exhaust, then back into duals right before the mufflers....talk about restrictive.