X Force Twin 2.5" Or 3.5"

[KWIK F6]

I have a 3.5 inch dump pipe with a 3.5 inch cat. Just installed a Mild Steel X Force twin 2.5 inch cat cak exhaust...Sounds awesome..Has a nice note on WOT. The exhaust mixed with the UB CAI sounds like a fighter jet..

[bjc]

The rear muffler on the 3.5in xforce system is a reasonable restriction. I cant say how much as I haven't had my car retuned yet but with just replacing it over to a mild steel (stainless was to exy because of the offset) straight through instead of the twin restrictive tip it held 2-3psi more across the rev range but due to pinging with any tune now I cannot dyno run for comparison until retune which will be a while away atm.

With my big tune in it will ping just before 4000rpm and with the mild tune just before 5000rpm.

If I have time and funds permit when I finally get it tuned by Dave at CPV I will change the muffler back over to the xforce one after it has been tuned with the straight through muffler and we'll see the difference for comparison.

[gregor]

bjc you dont say how much power and boost you are running

[bjc]

Tuning was done in Brisbane by Elite. Power was 337rwkw 25C day, 15psi taper to 14psi.

Moved to Townsville start of the year. Had power runs done up here a month ago maybe with same tune and best was 318rwkw, 35C temp same boost intially but only 13psi up top.

2nd run was 297rwkw which was done within a minute ish.

High boost tune as I wrote are 15psi but now hold near 18psi. Low boost tunes were intially 12psi flat but hold near 15psi.

Cant give you anything more atm as I dont want the motor to die. Do a search under my posts and you'll find both dyno printouts for Brisbane and Townsville.

[gregor]

that's weird, plenty of people seem to be able to hit 350rwkw with them, even more. If you were running 380 or something like that I wouldnt be so suprised. Could it be your cooler? What brand is it?

[bjc]

What are you refering to that is weird, the power figure drop from Brisbane to Townsville or the big power drop on the second run or something else?

IC kit is Rapids with 4in intake also.

I'm not saying the xforce isn't good and it does flow extremely well being 3.5in straight through except for the rear muffler, its the restriction. I have no doubt it can flow well over 350rwkw but with the change in rear muffler I am now seeing the boost spike and the engine ping so that is a restriction by the old muffler.

My BA motor and injectors (eugene's about 39lb inj) wont go that far safely, plus standard wastegate and actuator.

As I said in my previous posts my car needs a retune now anyway as I will be going with a bigger injector and will change the actuator and attempt a turbo port/flow myself plus the heat up here is very different to Brisbane (even though people still swear it isn't!)

[IH8TOADS]

Hey mate, have you got any pics of the new muffler (including outlet) and details of the muffler itself? I'm thinking of doing this.

There is a stainless magnaflow item (oval type) that has an offset inlet / outlet but as you said it's quite expensive @ ~350 buckeroos.

[bjc]

I quickly snapped these pics off for you but will get a wide shot of it from the back tomorrow as it does look good still even with the cheap muffler.

I was jammed in the garage taking these so not the best and couldn't get right behind it.

Dont know the brand, no name I guess just straight through with a stainless tip welded on!

The muffler being black with only the stainless tip actually doesn't stand out as much as the xforce one so is more inconspicuous on the car. The car is noisier on the outside and still very bearable inside, not droney just a deeper note.

[gregor]

What are you refering to that is weird, the power figure drop from Brisbane to Townsville or the big power drop on the second run or something else?

IC kit is Rapids with 4in intake also.

I'm not saying the xforce isn't good and it does flow extremely well being 3.5in straight through except for the rear muffler, its the restriction. I have no doubt it can flow well over 350rwkw but with the change in rear muffler I am now seeing the boost spike and the engine ping so that is a restriction by the old muffler.

My BA motor and injectors (eugene's about 39lb inj) wont go that far safely, plus standard wastegate and actuator.

As I said in my previous posts my car needs a retune now anyway as I will be going with a bigger injector and will change the actuator and attempt a turbo port/flow myself plus the heat up here is very different to Brisbane (even though people still swear it isn't!)

I thought it seemed unusual that the exhaust might be causing pinging at that power level given that others seem to be running more power through them. Like you are saying where you are probably doesnt help either. Good to know though if I hit the limit with one it just needs a muffler change. Would still be a lot cheaper than some other options too.

[bjc]

Yeah I'm not a tuner either so cant say myself, to much timing maybe? I guessed it might have pinged with the big tune but to have it do it on the lowest one was strange to. Could have been a bad batch of fuel to but I doubt it and is coincidence if it was as I hadn't filled up after getting the muffler replaced!

Here is a pic of the complete back end.