Well, being in this business, I can't leave well enough alone, lol. We have a customer who had a F1C Procharger on his car and he had some very nice Stainless Works Headers and X pipe on it. They are 1 3/4" primaries and 3" X pipe. This is probably too large for a minor bolt on car, but since I'm going to put a Whipple on and eventually build the engine, I decided to buy them from him. We are doing a custom turbo kit on his car and he doesn't need them.

To keep it simple, I installed the header and X pipe, and then just adapted the 3" X to the stock 2.5" catback pipes and left my Mac mufflers on. I wasn't expecting a ton since these are pretty large for what I have right now. I'm pleasantly suprised by the results. It's a bit too loud for my taste but the sound quality is good (not too raspy). As you can see by the run number on my graph, I do alot of dyno testing on my car! I haven't had it 2 months yet.

Before numbers: 270.53 rwhp 287 rwtq
That is with:
Modular Depot CAI
Mac Mufflers
4.10 gears
Stock manifolds and cats


After numbers: 288.56 rwhp 306.28
Only changes were the headers and off-road X pipe

That's roughly
360/380 at the crank

or

306 rwhp 323 if it were a 5 speed.

 

Nice gain for headers & X-pipe. Any guess as to what gains you got eliminating the cats?
I'm considering going with a O/R H & I've heard that just eliminating the cats gains approx 8-10HP.

 

288 at the wheels is 360 at the fly? Am I reading this wrong?

 

For an automatic. 5 speed you use 15% drivetrain loss and 20% for an auto. This is just an estimate and really doesn't mean much.

 

Ken, I am gonna have to come down and hear your car. I am jealous! Then when you get the Whipple on there can you take me for a ride?

 

Absolutely!

 

Nice numbers!

I see you don't mention a tune anywhere, so I'm assuming you did not optimize the tune for the headers? I wonder how much more there is left in them, if that is the case.

 

He's the owner of a dyno shop, I figure the tune is pretty sweet.

 

Yes, he is correct. My car is always on the dyno testing something new. And it's always being tuned. You can't really just swap headers on without a new tune from what we've learned.


Ken