Im just curious - has anyone w/ the vortech kit changed out their test pipes or open flow exhaust and replaced it with a more restrictive system - say hi-flow cats and a more restrictive exhaust (ie. nismo exhaust) - and as a result have you picked up more horsepower? I have a very open exhaust system and have read before that others are getting more whp when creating more back pressure. It seems to me that it would be the other way around.

 

aron...I had headers ,RT cats ,and a Stillen dual exhaust . The RTS failed and I cutted them . I only could make 7.6 lb's boost with the 3.12 pulley . I got tired of the loud exhaust so I added Crawford cats . I now have 9.5 lb's boost and after retuning I am making the same whp as before with 7.6 lb's boost . So if you like the louder exhust I would stsy with it . Im not for sure....some one correct me if wrong.....but .... I think its less stress on the motor having the open exhaust and less boost....than more boost and a quieter exhaust....Bill

 

I just throwing this out there, but does more/less boost necessarily equate to more/less HP? Meaning, is it possible to actually flow more air (cfm) at a lower boost pressure?

 

Thanks Bill...i guess it may not be worth it then to go for more boost, who knows?

I'll eventually be scrapping the borla anyways...after having it for over a year and bunping so many potholes / speed bumps, i think i have worn the thing out. It rattles and shakes, i think i may go with the Nismo exhaust, I hear everyone saying the sound in incredible. I'll probably keep the test pipes though, atleast until emissions comes.

 

I have the Crawford Headers & cats... showed over 9lbs of boost on the Split Second... best dyno was 425rwhp. Dynos ranged from 410-425... boost is good!

 

mc duck,

what are you getting for tq numbers? I netted 369rwhp, but only 298tq. It seems the setup u have with the crawford cats is the way to go. Of course I have 5AT, so maybe thats the problem

Aaron

 

aron..did you dyno on a Mustang dyno ? If so ..your whp and trq will run any where from 7% to 12 % lower than a dynojet dyno

 

Booger,

It was an AWD dyno done at AAM in Maryland

 

More back pressure equals more power with Vortech is false. I had the Borla TD exhaust and made 12HP more than with my current Y-pipe setup. However, I did gain some torque.

 

aron... even before I added the Vortech, it was obvious the Crawford Cats and Headers were the way to go. They added a very nice amount of torque down low. Not as much at peak, but my before/after dynos for the headers showed around 20-25ftlbs of torque gained from low rpm up to around 4000.

I don't recall off the top of my head what the exact peak figures I hit on torque were. I think they were just a bit under 350ftlbs.. .maybe 346 or 348.

 

What makes the added power is the added CFM , not just the measure boost pressure (MAP). You most definately can make more power with lower boost if the overall CFM ="Flow" is improved and tuned to re-optimize the A/F map. For example if flow is improved via exhaust or intake tract modifications most typically boost will drop with an SC. With a turbo the WG "closed -loop" operation will automatically (to point) keep the boost level at the point it was prior to flow improvements. With an SC , in order to re-add more boost requires a pulley change, but this is not necessary to see a power improvement