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If it eases your mind lots of 10 sec cars running around with 2.5 in systems.....their 20hp claim seems pretty optimistic as Ive done it myself but dont think it will hurt you going all 3" or 3 then necking down to 2.5 etc so you have options
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As the exhaust travels through the system it cools quick and doesnt really require as large a pipe at a a point.
Think of a C4 system like an old musclecar (long exh) that dumps by the rear axle
If you use a good straight through muffler (like dynomax ultraflows or) always a plus..and they sound awesome.
Thanks,I currently have flowmasters on it.I think I'll try to cut the 2 into 1 front part to separate the 2 pipes and hook them up to the 3" x pipe coming from the front.I to thought the claim of a 20 hp gain was a little optimistic.
I mis spoke when I said that I have flowmasters on my vette,I actually have borlas,The flowmasters are on my truck.Left brain wasn't working with the right or it was crs.
As for the difference between a 2.5 and a 3" ,I'm told by the dyno guys and my eng. builder it will be about a 20 hp gain on my engine.Can't quite decipher the rest of your reply from"it's your car though" on,but thanks for the reply.
There is a rule of thumb in place for hp ratings and size. 3" is where you need to be and if you do any more mods you'll be buying 3' anyways.
With 535 HP (is that an actual observed dyno number, or guesstimate based on the parts?), I'm thinking your 1-3/4" primary headers are going to be the restriction before 2.5" duals will be.
Mainly i wanted to reduce the drone, and increase the pitch @ RPM.
It helped the drone when crusing at low RPM, especially with those aggressive FM40's.
Higher RPM the car screams, sounds like a proper sports car IMO.
Coworker told me it sounds like an F1 car, and that's pretty much what i wanted...
Another thing it does is to increase the exhaust scavenging (helps to pull fuel and air into the engine), and exhaust pulses smooth out, i think thats part of why the tone changes...
And cruising the freeway @ 1200rpm, it still has a very nice rumble, almost motorcycle sounding.
But as soon as the converter unlocks, and the engine hits 3k rpm, the tone drastically changes.
Like night and day difference.
Top off and driving through a nice tight walled canyon, the car sounds like sex imo.
Mainly i wanted to reduce the drone, and increase the pitch @ RPM.
It helped the drone when crusing at low RPM, especially with those aggressive FM40's.
Higher RPM the car screams, sounds like a proper sports car IMO.
Coworker told me it sounds like an F1 car, and that's pretty much what i wanted...
Another thing it does is to increase the exhaust scavenging (helps to pull fuel and air into the engine), and exhaust pulses smooth out, i think thats part of why the tone changes...
And cruising the freeway @ 1200rpm, it still has a very nice rumble, almost motorcycle sounding.
But as soon as the converter unlocks, and the engine hits 3k rpm, the tone drastically changes.
Like night and day difference.
Top off and driving through a nice tight walled canyon, the car sounds like sex imo.
Mainly i wanted to reduce the drone, and increase the pitch @ RPM.
It helped the drone when crusing at low RPM, especially with those aggressive FM40's.
Higher RPM the car screams, sounds like a proper sports car IMO.
Coworker told me it sounds like an F1 car, and that's pretty much what i wanted...
Another thing it does is to increase the exhaust scavenging (helps to pull fuel and air into the engine), and exhaust pulses smooth out, i think thats part of why the tone changes...
And cruising the freeway @ 1200rpm, it still has a very nice rumble, almost motorcycle sounding.
But as soon as the converter unlocks, and the engine hits 3k rpm, the tone drastically changes.
Like night and day difference.
Top off and driving through a nice tight walled canyon, the car sounds like sex imo.
Just a note, I did some real world testing on my 16Z06 comparing the Corsa 3" midpipe with double X-pipes to Borlas 2 7/8" single x-pipe unit. The smaller Borla with only 1 X-pipe was consistently a tenth better in the quarter than the larger double x-pipe Corsa. Either bigger is not always better or a double x-pipe is not better than a single s-pipe or both.
Any bigger primary than the 1-3/4 he will probably lose some power and make changing plugs a hassle.
Won't lose power. May lose a little low end torque, but it'll be more than made up at the top end. How big the pipes are after the collector won't change the effect that too small of primaries will have.
Difficulty changing plugs is sometimes just the price you pay for performance.
I home built my own 3in exhaust. I re-using the original flowmaster mufflers (just opened them up for 3in) that came with the car. I probably have around $120 in my build so far. I'm running a 05 LQ9 with shorty headers, with no cross pipe at this time. I'm probably around the 400HP area right now. Sounds pretty decent.
You guys with long tube headers, your exhaust system would be super easy to build.
03-10-2017, 09:57 AM
