redstang08gt

I would love to buy an aftermarket exhaust from headers back expecially after what headers x pipe and flows done to my 93. I read on a ford tech article that an aftermarket exhaust on a variable cam timing motor doesn't help any unless modded with acharger and other power adders. Also it went on to say the factory exhaust flowed very well and could support up to 425hp. Has anyone with a all stock motor done theexhaust and dynoed thecar to see what the actual gains are if any? I would hate to drop that kind of money on something that isn't going to help. If it doesn't help I am going to buy a tuner and a cai

Daniel60

When I bought my Mac's axleback's I didn't gain horsepower in my opinion but I gained a sound that completes the total package. Now I'm looking at the Mac prochamber and love to hear what that sounds like. If you get the CAI go with www.brenspeed.com

Legion5

People who have mounted up SLPs would disagree with you. It definitely helps, a great example of this is people have dynoed their car with cutouts which allow you to instantly change the exuast from stock to a perfect ideal but loud exhaust.

The gain is somewhere around 35hp with the cutouts open or 12%.

Freer flowing exhaust helped non variable valve engines allong in the past because they helped make up for valving errors, ie even if the engine was timed wrong the gas would still have enough time to get out of the chamber, this is because the exhaust gas flow rate through the valve is exponential from start to finish so while a larger exhaust might give a 50% boost on a correct valving setup, it would give a 150% boost on a messed up setup. If you don't believe me, look up flow rates for gasses at different pressures and openings. I just looked this up because I was putting together some computer parts.

Anyway so on variable valve timing there is no valving error so it doesn't work as much as having a larger exhaust did on older engines, but saying it does nothing is very different from saying it does almost nothing.

This is my guess but if you buy an after market exhaust it probably does almost nothing if you want to keep the same noise level, it's not like they put in a bigger mid-pipe in most exhaust systems, and that's going to affect exhaust the most if you consider that this is where most of the exhaust gases spend their time. Maybe worth 5hp or less.

howarmat

N/A engine with new o/r midpipe might get you 5-7 HP
new axlebacks are not getting you anything measurable
New LTs around 15 maybe in the higher RPMs
Shorties can get some good midrange HP but not much in the higher end

captainxanax

Recently, I have had to explore all my options on the exhaust due to a bad CAT.

I have the stock H-pipe underneath with an o/r set-up. Stock mufflers for now.

The car sounds really good, and that causes a "head/mind" trick on speed... everyone knows that... it is like 'black' is speeding while sitting at a red light...

But I live at 7000' and can feel the performance here. When I drive to PHX, I can tell the elevation changes without the signs.

I swear I picked up, or tapped into, or unleashed something on the car and it just seems 'quicker' on the same roads I have been driving stock for 2 years.