Open flash header and catless front pipe and unresonated exhaust review
 

I just installed my OFH combo with P&L over pipe, P&L catless front pipe and unresonated perrin 2.5" exhaust.

My original intent was to reduce the torque dip with the stage 2 open flash tablet. The gains and improvement is incredible. The only drawback for this set up is the extreme drone and rasp. I don't mind the loud exhaust drone but the metallic rasp is gets annoying at high rpm over 3500. I realized that for a daily city driver it may not be ideal both for the rasp and raw exhaust smell.

I am now contemplating on getting a high flow catted front pipe.

It gets embarrassing driving a 200hp car that sounds like a loud Honda fart can.

I don't think there is a huge loss of torque and hp going to a catted front pipe. I tried looking up and did not see many discussion.

Thoughts? :burnrubber:

get a resonated mid pipe for the perrin, (or have one welded in) and get a resonated or catted front pipe. (or again have one welded in)

I ran a fully catless set up with a resonated front pipe (Helmholtz) and resonated perrin and i had 0 rasp.

How many times can this question possibly be asked?

If you are going to run a catless exhaust system, you MUST use at least two resonators.....HKS dual resonated front pipe and cat-back resonated will eliminate drone.

Go back to stock catback. Try it. Should be a simple swap out.

Thanks for the feedback guys. Didn't mean to beat this topic to death.

As mentioned I don't mind the drone. I just didn't anticipate the rasp to be that bad. I will definitely look into a high flow catted front pipe in the near future.

As mentioned a resonator wil help with the rasp. A 200 count HFC won't help much, but it will a bit.


I cant get over the fact that people are shocked that these cars get raspy when opened up. The more retarded the timing, the more retarded the exhaust cam gets, and the higher compression the engine, the louder, higher pitched, and raspier the exhaust note gets. That's just how the car was designed. It's like complaining about a diesel engine that knocks... Our cars sound like a Honda because the FA20 basically a flat K20... with poorly designed heads, so it makes less power.

When going cat-less, resonators are your friend!

@Shiv@Openflash
What about tossing the OEM front pipe back in? Would that make a difference? Is the stock front pipe, in your experience, too restrictive for car with just bolt ons?

Just want to throw this out, I ran a Open flash header with stock OP, FP and catback and dyno'd 205whp on E85.

Nearly nothing past the header is restrictive if you're Naturally Aspirated. Honestly, maybe 2-4hp gain if you change from stock.
In addition, whenever you pair a header with ANY catback it will sound different and way louder than the catback with stock header (where most designers test)

My .02

you might lose a bit of hp and gain some torque. that's about it. what i have seen posted is some people get a weird resonance in cabin from the stock front pipe (and everything else aftermarket). could be because of the resonator it has, but i'm not sure.

Just curious. Would getting just a Perrin resonated mid pipe still would not be sufficient to cut the rasp?

From everyone's comments I am starting to reconsider looking towards getting a proper resonator instead of the catted front pipe.

Just wondering if one Perrin resonated mid pipe would be enough or would the HKS dual resonated front pipe be the better option?

From what I think... The Perrin should have a longer resonator on the mid pipe as opposed to HKS two smaller resonators?

i mean, going either option will do a lot to cut out the rasp, but i'm unsure if one or the other will be sufficient or if you'll truly want both. It might be most cost effective to just have a muffler shop add the long resonator to your mid pipe and drive that around for a bit and see how you like it. if its still too raspy then go a-head and add a resonator to your front pipe :)

It's going to cut out a lot of the rasp, but not all of it. I added a vibrant resonator to my HFC Berk Front-pipe, I have a HUGE Magnaflow resonator, and there is still some rasp. I have zero drone, and zero rasp at light throttle and just regular driving, but once you get into it, it's raspy, but I like it. It sounds like any other modern NA engine. The Jaguar F-Type and 911 GT3 have some rasp at the top of their rev range.

Not an OFH, but the stock resonator on the mid-pipe does a pretty good job at cutting rasp. No cats or other resonators in my system.

[ame="https://www.youtube.com/watch?v=eNiwGXRrQC8"]Scion FR-S Tomei UEL - YouTube[/ame]