OLDSCHOOL85

iTrader: (10)

Anyone experience loss rwhp on the dyno.. with Borla exhaust plates in instead on no platesat all.

If so, How much?

GMCHammer

iTrader: (4)

If I remember correctly, my buddy went from about 375hp with the 75% plate in to 390hp with no plate at all. I know that we where shocked on how much power the plate was robbing!

OLDSCHOOL85

iTrader: (10)

Wow - That is alot of hp the plate robs...

ajrothm

I put a QTP electric cutout on my borla in place of the plates. We dynoed it closed, 1/2 open and full open, on both motor and spray. With the cutout open, we made 390rwhp, with the cutout closed, 392rwhp.... 1/2 open was 391. We did the open pulls first so it might have actually made more power with it closed on a less heat soaked run. On the spray(with a near empty bottle) it was right around 540hp either opened or closed. Apparently that big *** borla muffler flows pretty damn good.

This was with Pacesetter Lts, TSP OR/Y.

I have found that running the cutout ALMOST fully closed, but barely a crack open sounds the best. Still get that good cam crackle out of the right side pipe but most of the exhaust(like 95% of it) comes out of the left and there is none of the raspy **** at 2000 rpms like usual.

ScreaminRedZ

iTrader: (3)

Haven't tested mine with the current, cam-only, setup, but with just a lid and the borla I was only losing about 1.5-2 rwhp with the smallest (non blockoff) plate over the wide open plate. I would assume that as you make more power it would become more of a restriction. I think I'm just going to put an inline 3" cutout right after the y-pipe with an electric cutout.

Redlinez

iTrader: (5)

Yea, I took a solid plate and drilled a few holes in it until I got the desired sound and very little rasp. Funny how those plates really don't affect HP very much. I wonder how the Borla performs vs a Hooker.

moeZ28

iTrader: (7)

It depends on your tune and your cutout placement. My old car had dual cutouts right after the long tubes, and picked up 21 rwhp on the dyno in back to back runs with the same tune. After a retune with the cutouts open, they picked up another 7 or 8 rwhp over the previous 21. However, the retune was optimal when they were open. Closed the car would run a little rich. 13.6:1 open Air/Fuel ratio, 12.8:1 closed Air/Fuel ratio. If your car is tuned to be optimal with the cutout closed, you may see a small gain or even a loss as your car will run leaner with the cutout open.

ajrothm

That borla muffler is huge, I think its 19" long and 4" thick but its straight through, you can put a broom stick straight through it....I don't think it hurts the flow at all.....

I will be dynoing again soon to see the loss from my 9" install and I will test the borla/qtp again with a full, hot bottle and see if it hurts it any but.....I really don't think it does.

Also, by running the borla ALMOST fully closed, you get a good tone through the exhaust when accelerating but NO RASP at all.......I just crack the qtp open about 1/4", just enough to get the cam crackly sound coming out of the right side but MOST of the exhaust still goes through the muffler....its a great blend of racket at idle and smooth/toned sound on the gas hard. I was not real happy with the borla until I installed the qtp. Fully closed was way too quiet at idle, and with ANY of the adj. plates in it, it developed that horrible rasp... Glad all that is fixed now.

Hardtop

iTrader: (3)

My 2001 H/C Z28 lost 7 rwhp with the plate closed. Sounds alot better closed than open.

96ta

i threw away my plates i didnt see the need to have them at all

ScreaminRedZ

iTrader: (3)

^That makes no sense. You weren't using them at the moment so you tossed them? It's not like they take up space.