Hi-fow vs no cats, (will be supercharged eventually)

[Invasivore]

I have to make the decision now whether i should go with high flow vs no cats. Right now, i just have a cat back and smooth tubes. I will be supercharged hopefully within a year though. Is there a substantial difference in power potential when i put the paxton on it?

 

[g3t_t0rk]

Probably 0 difference in whp gains. I got no cats cuz I've had too many problems in the past with them clogging up! Plus they sound so much meaner and flames out the tailpipes is a plus

 

[Fuoss484]

I have the cats deleted on my GTS. This winter I will be putting some high flow cats on.
As of right now, I get a lot of exhaust fumes in the cabin, if the window are down. Windows up, no fumes. Read somewhere that a high flow cat will correct this.
Really dont think it will hurt HP significantly, with the paxton (but not an expert on this).

 

[speedracervr4]

I run high flow cats on my Roe car (since 06) and I've had no issues. I've been told it will lower your HP by 5-15hp, but I would rather not deal with the soot or fumes.

Fuoss484, Have you checked your rear exhauster vents in the truck compartment? They fall down sometimes and allow more fumes in than normal.

 

[GTSPOWERED]

No cats no fumes no problems great sound.

 

[Allan]

I like no cats.


3" non-restrictive pipe is the way to go.

 

[uvbnbit]

I ran catless for 6 yrs. great sound. got tired of the fumes, stains on bumper, clothes in trunk smelled. Maybe i just getting old . I put hi-flows on this spring and LOVE IT! car has a better "tone", no exhaust smell, it actually feels "stronger"? I hear what you lose in HP, you gain in a bit of TQ. They say "some" backpressure is good. I did a search online and found a ton of scientific, engineering stuff that was waaaay over my head on that topic.

I have 2 3" cat delete sections. make offer

 

[DrumrBoy]

Don't delete the cats for WHP gain....you won't notice anything at all. Delete them (as I did) for the sound and for the sill heat lowering properties of going catless.

 

[Detlef]

And for shooting flames out the tailpipes when lifting off of the throttle.

 

[g3t_t0rk]

Some good info regarding backpressure and exhaust set ups.

http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm

 

[NO HEMI]

Very interesting read, so going by what he said , me having no-cats and just
One small bullet muffler on each side ( even though it's loud), is probably the best setup for my hp range!!!

 

[whitebluevipe]

I run roe hi flo with no problems

 

[VIPER BAZ UK]

No Cats and the two side muffler Borla exhaust set up .... No issues at all ... Flames are cool.

 

[brentsGTS]

Pull the cats for better power. Plus it will sound better and have lower temps. Less restrictions equal more air being allowed in! Besides only ******* run cats.

 

[plumcrazy]

what he said

 

[uvbnbit]

I'll be right back, I need to re-******

 

[Blainne]

Don't delete the cats for WHP gain....you won't notice anything at all. Delete them (as I did) for the sound and for the sill heat lowering properties of going catless.

I have Hiflow cats and my sills stay cool, but I'm even up in the air going catless for the sound. (Viper had Hiflows on it when I bought it.)

 

[plumcrazy]

catless, the sills are ice cold. not heat at all, even in summer. you wont have to worry as much when you add boost. the SC cars tend to run rich causing cats to clog. when they clog, they can cause severe engine issues, dont ask me how i know

 

[Jack B]

I have personally seen two major cat caused fires on modded cars. Early Roe's also had an isse wirh cats igniting due to a rich a/f mixture.

 

[Invasivore]

I have personally seen two major cat caused fires on modded cars. Early Roe's also had an isse wirh cats igniting due to a rich a/f mixture.

I think im sold on going catless. I don't want any potential for a fire, i plan on keeping this car for a long time. Plus I didnt even think about if I wanted to run leaded fuel on a good tune

 

[mtmclaughlin]

Plus I didnt even think about if I wanted to run leaded fuel on a good tune

What? Why? Are you talking about aviation 100 LL?

 

[Invasivore]

What? Why? Are you talking about aviation 100 LL?

They sell 110 leaded and 100 unleaded at the pump by my house

 

[DrumrBoy]

They sell 110 leaded and 100 unleaded at the pump by my house

Whoa, THAT is incredibly cool. Is the 110 leaded priced under $10??? I may have to move ;-)

 

[Invasivore]

Whoa, THAT is incredibly cool. Is the 110 leaded priced under $10??? I may have to move ;-)

Yeah, I haven't been there in a while, but they would not let us fill up with the 110 leaded unless the car was on a trailer, or not until midnight

 

[Invasivore]

BTW, has anyone made near 700 rwhp on pump gas on a stock motor with a paxton and headers? I hear about this Novi 2500, but haven't thoroughly researched it. There are pesky GTR's in the area that I think have trap speeds in the 136-138 mph range. I know it will take about that kind of power to match them.

 

[plumcrazy]

you live in the same town as DLM, go talk to doug, nobody knows more about paxtons on vipers

 

[Bill Pemberton Woodhouse]

Keep in mind going catless is going to make it hard to resell in many States and frankly the comments on fumes in the car and around should be taken notice -- we had a ton of complaints over the years from customers who modded and then wanted to put them back.

 

[Invasivore]

Keep in mind going catless is going to make it hard to resell in many States and frankly the comments on fumes in the car and around should be taken notice -- we had a ton of complaints over the years from customers who modded and then wanted to put them back.

Are these reports of fires from only the stock cats or modded hi-flows as well?

 

[Dom426h]

Prob mainly stockers & older hi-flow ceramic substrate ones.(failing)

The hi-flow metal substrate ones are suposidly more durable. Makes sense to me since they flow better meaning less heat buildup. Only downside is that since they flow like a straight-pipe they Sound like a straight pipe.(as where the ceramic ones aid in taming the sound)

Yes, the fumes of going catless can get to you. Do you wear contact lense? Keep an extra bottle of clear eyes drops in the glove box

 

[plumcrazy]

some of the fumes can be tuned out.