I think the testpipe makes the car sound good at wot but for everyday driving it makes the car sound too hollowed out at low speeds and not very good. I had my test pipe on for 2 days and hated it.

 

Yeah but almost a 20WHP gain at peak and 7+ throughout the range; that is HUGE not to mention what would happen with larger turbos.

 

What problems, if any, will you have if you get tuned with a test pipe and use a HFC most of the time? I want to get tuned for the test pipe but use a cat for everyday driving.

 

I wish I had this post a couple months ago when some clowns were arguing with me how the gains from a cat delete were negligible over a HFC

It feels like you turned the boost down 3-4psi when you put one of them on after having a cat delete. I'm sure some can attest to how bad it is when you put the stock cat on after a delete to pass inspection...

 

That is my cars dyno sheet, i have a full buschur TBE with magnaflow, and o2 housing and slowboy racing exhaust manifold. The difference in the car is very noticable from the hi flow to the test pipe, the car pulls harder especially at redline. The sound is tolerable at low speeds and cruising around town and at WOT is sounds amazing but loud. I have the cosworth cams which give it a very nice sounding lopey idle which i particularly like. The boost is set at 23psi. Thanx again Al and Jimmy at "the shop" great job with my car. I'll see you guyz at the end of the summer to put in that alchy kit.

 

I have an idea for a great product

Get the QTP guys to make a electric valve that switches from a catted side to a test pipe side with a switch in the car

One side is quiet and smog friendly - the other is good for more power and sound

At this point they have it do it dumps to the air which makes the car stupidly loud

I dont see why plumbing could noty be installed to switch between say a high flow cat or resonator on one side and a straight through pipe on the other

 

Thanks man

Alchy will get you just over 400 tq and 380 whp or so on our dyno

 

Al, give em a PM...

 

Al, since there was a molestation of the fuel map after the test pipe was put on...will the car give the same result if it were to have the same AFR with the hi-flow cat on...on the same boost?

 

nice if you had the AFR-MAP plot of both run 016 and 021

 

The car was simply too lean just pulling the HFC it needed some fuel to be safe

 

Doesn't the MAF sensor usually adjust for minor exhaust mods? I'm surprised that it changed the AFR that much. Could it have been pulling some timing with the cat and then timing went up with the test pipe (thereby leaning it out)? I'm just wondering if there was a timing change also between the two runs.

 

It certainly would. The Car would knock, the ECU would pick it up and YANK timing, and possibly less power would be had with the Cat on in the 1st place. Tuning is Key, it's why Al has a Job

 

I dont think it went THAT lean to to warrant pulling significant timing out, but just from the added flow and going a little lean, the power gained would be mucho compared to maybe 1 degree of timing.

 

No no. I'm wondering whether it was knocking on the original tune with the cat (due to too much timing and boost for the amount of exhaust backpressure from the cat), in which case it would have pulled timing and run richer than if there were no knock. Then, when you put the test pipe on, the knock might go away (due to freer exhaust) and timing would rise to the full extent of the high octane map value, thus leaning the car out due to more timing and possibly a leaner high octane map.

Was this car tuned with the cat first? Or was the intent to tune with the test pipe, so the pass with the cat was just a baseline?

Al, please don't take these questions as an attack. They are not meant that way at all.

Thanks.