I think that's a good plan. I can't speak to the smell that you've asked about.

I've got Kooks 1" 3/4 LT's, high flow cats, and the stock G8 GT mufflers and even with the cam and other stuff, it is relatively 'quiet'.

I'm thinking of adding some Magnaflow mufflers or Kooks Gen 2's maybe (something inexpensive) for some more exhaust sound.....

 

I've listened to a car with AR LT's and stage 2 cams with stock GT exhaust and was astonished with how quiet is was. The stock exhaust is a masterpiece at keeping things quiet.

 

I know, I totally agree with you.

With my Kook's LT, high flow cats, & stock axle back the car is just a tad too quiet.

That's why I'm looking for a nice rumble or throaty axle back with no drone...



...

 

I have also heard a car with both Kooks mids and the same car with the Solo HFC's along with the GXP exhaust with the mid muffler delete and x pipe and it was still fairly tame with no drone. It definitely had a more muscular sound than the GT setup, but it wasn't loud at all.

 

I just got my Kooks Mids that I will be installing soon to the stock exhaust. I am hoping it will be quiet, as in I hope my wife can't notice.

I have the DMH "Low Profile" Cutouts that i can open if I want it loud.

 

I'm going to be installing the Kook's 1 7/8" Kooks long tubes with their catted 3" x-pipe and factory GT mufflers...I'll post a video for you when it's done if that helps...

 

I have a similar set-up (1 3/4 headers) and its deceptively quiet. No one knows what you got until its too late.

 

sounds good, i think using the gxp midpipe with the 2 pup cats, and the small resonator, with gt mufflers will really help offset the sound of headers with no cats. i just wonder what the inside of the pup cats look like. if they are a real cat or just a straight threw cat. hopefully they are like the stock ones just half the size. if so that would really be good for keeping the smell down, but still letting a good amount of exhaust threw

 

Most people see a gain of 25 - 40 HP at the wheel after installing a CAI (Roto-Fab, VCM, Vararam, Volant, etc) and a tune (VMS, Livornois, etc). Approximately how much HP gain is there from adding headers (ex. headers listed above) to the CAI/tune and maintaining the remaining G8 GT exhaust?

 

Most people see a gain of 25 - 40 HP at the wheel after installing a CAI (Roto-Fab, VCM, Vararam, Volant, etc) and a tune (VMS, Livornois, etc). Approximately how much HP gain is there from adding headers (ex. headers listed above) to the CAI/tune and maintaining the remaining G8 GT exhaust?

My before dyno (Roto-fab, Stage 2 Ported TB/Manifold, Tune) was 321hp/336tq and my after (ARH 1-7/8" LT & high flow cats) was 351hp/364tq. All keeping the stock axle-back.

 

I've got Kooks 1" 3/4 LT's, high flow cats, and the stock G8 GT mufflers and even with the cam and other stuff, it is relatively 'quiet'

Do you have the Kooks x-pipe as well?

 

What about LTs and no cats? Anyone running that?

 

What about LTs and no cats? Anyone running that?

I picked up 40rwhp with DT's and x-pipe in place of pup cats

 

i just picked up the gxp midpipe, which has the 2 in 2 out resonator and 2 pup cats, i plan to install this with g8 gt factory mufflers, and doug thorley catless headers, im not worried about the emission or cel codes, i just dont want it to smell too bad, i hope the pup cats can do their jobs, and if they are taking 6 hp from me i bet they do something...

 

This is a tough question to answer as most people post their dyno runs after everything is installed. Hopefully someone can post accurate numbers. I can say without reservation that the pup cats on the 09.5's take away 6-8hp/tq. While I don't have numbers on the main cats, they are the one area of the stock exhaust that is the most restrictive. The stock manifold isn't too bad, but can certainly be helped by adding Long Tube headers or Kooks mid length headers. Adding just shorty headers just isn't a good price/performance modification and they don't add much hp/tq, especially when the stock cats are still in place. Based on some facts and my personal observations, pairing either high flow cats, long tube headers or Kooks mids w/cats will remain reasonably quiet and continue to flow well. It will add volume to the stock exhaust, but it's not a tremendous amount and it certainly didn't drone in the cars I listened to.

 

This is a tough question to answer as most people post their dyno runs after everything is installed. Hopefully someone can post accurate numbers. I can say without reservation that the pup cats on the 09.5's take away 6-8hp/tq. While I don't have numbers on the main cats, they are the one area of the stock exhaust that is the most restrictive. The stock manifold isn't too bad, but can certainly be helped by adding Long Tube headers or Kooks mid length headers. Adding just shorty headers just isn't a good price/performance modification and they don't add much hp/tq, especially when the stock cats are still in place. Based on some facts and my personal observations, pairing either high flow cats, long tube headers or Kooks mids w/cats will remain reasonably quiet and continue to flow well. It will add volume to the stock exhaust, but it's not a tremendous amount and it certainly didn't drone in the cars I listened to.

Thanks for the info. The people I know personnally who own G8's haven't touched their exhaust, so I'm not familiar with what to expect from exhaust changes on our cars. I don't want to spend $1K+ on an exhaust that is loud/drone, or one that is fairly quiet, but only gains 10 or 15 hp.

 

I just switched my exhaust setup to Kooks longtube headers and x-pipe with highflow cats and went back to stock mufflers. It is barely louder than stock. I miss my Corsa exhaust and will be getting some axlebacks this week. If quiet is what you want go with longtubes and stay with stock mufflers. The stock mufflers only lose about 3hp. The manifolds and x-pipe are where the restriction is in the stock system.

 

The LT with no cats with x pipe and stock axlebacks is the way to go for gaining the power and keeping it quiet! I've got the ARH 1-7/8 LT's, non catted x-pipe, with the stock GT axlebacks and the thing is waaayyyy too quiet LOL. It does make decent noise when you get on it. No drone, period. Great for those seeking the gains without the noise. I'm going to move to the Solo J's to get the noise level up. Hopefully they'll keep the drone down, but if not, oh well

 

I just modified the front half of my exhaust 2 weeks ago at an exhaust and dyno shop and did a before and after dyno to see the results of my $1300. They installed Kooks 17/8 LT headers, Kooks HF cats 2.5" in/out, 2.5" x-pipe, and 2.5" pipe to connect the three pieces. I kept the exhaust stock from the dual resonators back and it barely sounds louder than stock. My Vararam made a bigger difference in sound than my exhaust. Too quiet if you ask me and I don't like loud exhausts.

Before: 320hp/335tq (Vararam, VMS 93 tune)
After: 340hp/350tq (added VMS exhaust tune, Kooks 17/8 LT, Kooks HF cats 2.5" in/out, 2.5" x-pipe, and 2.5" exhaust pipe)
It made no power down low, 15hp in the mid range, 20 at the peak, and 28
near redline.

At the 1/8th mile track it dropped .13 seconds and added .9mph (8.63@83.9mph). VMS is currently working to try and extract more power from the new exhaust.

Chris
Navarre FL

 

I just modified the front half of my exhaust 2 weeks ago at an exhaust and dyno shop and did a before and after dyno to see the results of my $1300. They installed Kooks 17/8 LT headers, Kooks HF cats 2.5" in/out, 2.5" x-pipe, and 2.5" pipe to connect the three pieces. I kept the exhaust stock from the dual resonators back and it barely sounds louder than stock. My Vararam made a bigger difference in sound than my exhaust. Too quiet if you ask me and I don't like loud exhausts.

Before: 320hp/335tq (Vararam, VMS 93 tune)
After: 340hp/350tq (added VMS exhaust tune, Kooks 17/8 LT, Kooks HF cats 2.5" in/out, 2.5" x-pipe, and 2.5" exhaust pipe)
It made no power down low, 15hp in the mid range, 20 at the peak, and 28
near redline.

At the 1/8th mile track it dropped .13 seconds and added .9mph (8.63@83.9mph). VMS is currently working to try and extract more power from the new exhaust.

Chris
Navarre FL

yeah you would think you could make more then 20 hp with long tubes, maybe if you get the tune right there is another 5-10 in there.

 

I have the stock mufflers with the mods in my sig and I make good power. The exhaust is still quiet though.

 

LTs with a catted xpipe and stock mufflers is very quite and doesn't attract any attention from Johnny Law . My car makes 430hp with a cam and this exhaust.

 

You trapped 117 with just a cam and 430 to the wheels?

 

Well, thanks for all the info guys. looks like my planned gxp midpipe, with pup caps, and Doug thorley LTs, with stock mufflers, should be tame enough for me.

 

One my G8 GT I had Kooks LT headers, catted X-pipe, and Magnaflow. This was good sounding and quiet. Then on my GXP I have the same headers and catted X-pipe with SLP Powerflo. I actially really like this setup. Not loud, and no drone..but very muscular.