Mods: Intake, Pettit ECU, Full exhaust, upgraded SMIC, 13psi

I used to have just an HKS dowpipe and some other aftermarket catback system with a stock midpipe and I would pull away from my brothers Mustang easily on the highway.

I then installed a 3" midpipe with highflow cat. We then went to the track last weekend and I was side by side with my brother and wasn't able to catch up.

My highest trap speed was 108mph.

I am wondering if this has ever happened to anybody before and if that trap speed is accurate for my mods.

Thanks guys!

 

First off you cant have a high flow cat with a midpipe...

 

What?

 

Do you have a boost gauge? Be very careful when running that sort of exhaust combo without knowing what you're actually boosting at.

 

Yes looking at the read out on the Profec B. I have ported the waste gate and I dont have any boost issues.

 

he is meaning a mid pipe refers to a lack of a cat, midpipe = cat replacement. A high flow cat is just called a high flow cat not a midpipe

 

Ok but you can install a cat on an aftermarket midpipe lol

I should add that the cat is almost new. About 3000km on it.

 

My FD is actually running a similar combo:

1. Downpipe
2. Highflow cat
3. Resonated midpipe (right after the high flow cat)
4. Catback

So you're saying you have all that installed?

 

What cat are you using? The stock cat actually flows extremely well. There are very few aftermarket catalytic converters out there which flow more/better than the stock cat. The only down side is the stock piping is smaller than 3".

 

Agreed. Other than that I would say stock pieces are more on the heavy side, I mean, look at the stock pre-cat, I could do military presses with that bad boy!

 

It is just an aftermarket high flow cat. Not sure what brand. I thought it would flow better than stock piping with that huge cat but I guess I might have been wrong.

 

So you made a midpipe into a high flow cat, a midpipe would have NO cat installed at all. You confused a few people with that

 

ok haha, to me a high flow cat is just the cat itself with no piping attached to it. Anyways doesn't matter.

 

Is there a place that shows how these parts flow, that way you can compare them? It would suck to put in an aftermarket ( high flow ) cat, and lose power.

Has anyone tried random technology or the one at the rx7 store?

 

well from my understanding, a midpipe is a midpipe whether it has a cat or not. now a test pipe doesn't have cats.

 

It would be nice to know up to what kind of HP the stock midpipe/cat is good for.

 

Now that the terminology lesson is out of the way.......

A high flow cat VS. the original cat likely wouldn't make the difference you are speaking about. Especially since the cat you put in is utilizing a 3" pipe. What flow you would loose over the stock cat is likely miniscule considering the pipe enlargement with the aftermarket cat....

That said,....is that all you have changed? Are you running the same boost?......how much noticable power difference?

 

When was the last time you changed your plugs and cleaned your filters, etc?

Also, what were your intake temps like?

 

The difference is a good 2-3 car lengths per gear. I found it strange that after I put on the 3" midpipe I actually had to turn up the boost controller by a few % points to get the same boost levels as before. Besides that I also changed to a fluidyne rad but don't see what that would affect in power. Everything else is the same.

Plugs changed last summer. They could probably be changed again. Don't know intake temps as im running Pettit ECU.

 

Old/fouled plugs and high intake temps can/will easily kill your horsepower.

Maybe the cat that you welded on your MP is actually causing more restriction then the stocker??

 

Midepipe next to stock cat

Highflow cat

 

I think Im going to try and make a comparison since I still have the stock midpipe.

 

thank you force13b, i didn't like how he thought the mid pipe was a cat

 

You're getting wrapped around the axle on a stupid matter of semantics. He's been speaking about having a hi-flow catalytic converter in his middle (Mid) pipe (as in, not the DP, and not the cat-back) all along.

This was already thoroughly beaten to death once in this thread.

And, while we're on the subject, of you want to be ABSOLUTELY accurate with ALL terminology, then anybody who is running a free-flow exhaust system should be castigated for referring to their cat-back as a "cat-back".

 

hahah thanks fendamonky! The point of the thread was just to see if anybody else has been through this before that is all.