Okay, so I install the Borla and I've had it on for about 2 months now. I've been running it wide open on the street because I like the way it sounds. The problem I feel as if I'm having is that I'm not putting out the performance that I used to. Like the car has lost something.

Here is what I think the problems might be.

1. Stock knock module. Perhaps under hard throttle the timing is off? I've already ordered an LT4 one but it hasan't come in yet.

2.Back pressure. I have all the plates, maybe I need to throw one in there? Which one would be good for the basically stock LT1 with stock manifolds?

Or is it both combined?

Can someone please offer some suggestions?

 

I think what you are feeling is the loss of lowend Torque that a free flowing exhaust will exhibit.
When I first got my 94 I took the muffler out and ran a straight pipe in its place, car sounded bad *** but felt weaker around town. I bought a Mac catback used from a now defunct speedshop in town and it picked up alot.
Basically you will lose some lowend oomph but you gain it on the big end.
Does your car seem more powerful at WOT?
Try one or more of the plates in your Borla and see how it does, pretty easy to change em out.

 

you lost NO low end tourqe. I dynoed on the same day my exhaust open and closed. open i gained 1 RWTQ. the curve did not change AT ALL. My HP went up 7 RWHP.

you could be feeling the effects of summer heat, or bad gas, or maybe in need of a tuneup.

 

A dyno pull will tell you what you made top end, as in Throttle WIDE open.
We are talking LOW speed here not a top end dyno pull.
You will make it up on the top end, everyone knows that but it will feel less powerful down low with an open exhaust than with a good catback.
I can prove this with my car right now, its running header mufflers and thats as close to open as you can get. It does not pull at part throttle like it did with the catback but it screams at WOT and pulls like a raped ape with the near open exhaust.

 

Its probably two things. One of which is that you need the LT4 KM. The louder exhaust is probably being heard as false knock, and the computer is dialing in false timing retard.

Second thing is, the newness of the extra power has worn off, and it just feels normal now.

 

my dyno pull was form idle to 6k. I am pretty much stock.

 

I have never seen a dyno like that.
They get the car into 4th gear which is 1: 1 and then go WOT and record.
On automatics they get it into 3rd gear and then make the pull.
I am not trying to start a fight, its just been my expierence that you feel a low end loss of torque with an open exhaust.
Now you more than make up for it on the top end and as I have said before, how much racing do you do at part throttle.
Go with the open exhaust cause it WILL make more power but it might feel a little doggy just driving around town.

 

I think he could be right with the open exhaust. The KM is what I think I really need though. I run 94 gas all the time.