A couple of weeks ago, I decided that a V8 should sound like a V8.
I have driven 2 V8's with full exhaust modifications, headers, big cats, 2.5" pipe and straight through mufflers, and while it was a blast driving through the hills with the windows down, they were both a bit noisy for normal street use, both outside and inside the car.
Not having heard or driven any other V8's with modified exhaust, I decided to try a few things, and keep the exhaust modular so I could replace the original system if needed, e.g. in case I sell the car at any point.
I removed the rear mufflers, took about 30 minutes to just unbolt them and leave the rest of the system in place. This was very successful, a bit of a burble, not too loud, though there was a bit of drone inside the car probably due to the pipes finishing under the car. By the seat of the pants method, the car felt a bit freer from the mid range up, I noticed more tyre chirping powering out of corners on the Eagle.
Thus encouraged, I started talking to various exhaust fitting shops, that was an interesting exercise in itself. My overall impression was that they just wanted to sell you what they had at inflated prices, e.g. the mufflers I could buy for $160 each, the fitters wanted to sell me for about $250 each, and they would prefer to sell me whatever brand they mainly used instead - for about the same price. "All mufflers made the same way, i.e. double offset straight through's, will perform and sound the same, so you might as well have these which we already have in stock" Well, no thanks, I have done enough homework to know that they aren't the same, either in flow rate or sound quality, so credibility for the industry isn't high in my opinion.
I was thinking of just getting some pipes made to replace the mufflers, but the middle mufflers are also very restrictive so I wanted to remove them too.
I bought a pair of Lukey stainless steel double offset straight through mufflers, and booked the car into one of the few places that didn't have a "bad" attitude, and was happy for me to supply the mufflers. The car was still being finished when I called to collect it, and when it was back on the ground, we fired it up for the first time having no idea what to expect.
Initial reaction - disappointment. I had removed the 4 restrictive mufflers and replaced them with 2 straight throughs and 2.5" pipe and the car was about as quiet as it was when standard though with a lower tone. I had been expecting it to be louder than when it has the 2 rears removed with the 2 mid mufflers in place. It also lost most of the burble it had gained with the rears removed and was a bit more of a smooth drone sound.
After driving it a bit, I am now happier, as it is back to being quiet inside the car which gains the approval of my significant passenger in life, and it does roar a bit when pressed. I suspect the Y-joint behind the centre resonator is to blame for the loss of burble. It was fabricated by squashing the two 2.5" pipes into a single 2.5" pipe meaning both outlets are flattened on the inside and restricted. This technique is apparently used on the Holden V8's, but that isn't a recommendation in my view. The fitter also said the mufflers will burn in a bit over the next couple of weeks, so I should wait before making a decision where to go from here.
Feeling a bit frustrated I figured 6:00am was a good time to do an Eagle run which would also help with the burning in process. After reaching the top (I love that road!), I tried a couple of standing starts. With a view to going to the street car drags in the near future, I wanted to get a feel for how many revs to pre-load the engine to before dropping the brakes.
First run, I went to about 1500 RPM and dumped it. Wheel spin and axle tramp. Hmm.. that hasn't happened before, I usually need to rev harder than that to get spin. So I then tried just a standing start with no pre-revving, just left foot off the brake and right foot to the floor. Again I got wheel spin and some axle tramp.
This was getting interesting, I locked it into first went to about 45 kph and just floored the throttle and again, got a bit of spin but not enough to tramp.
On the way back from the Eagle, I pumped it a bit from the Cross Rd lights and got wheel spin about half way across the intersection. I backed off pretty fast as it's a busy inter section, intersection, so it would be interesting to see what would happen if I really floored it there - with or without pre-revving.
So, right now, I am very happy with what appears to be a significant improvement in performance with not much noise increase. Now I just have to decide whether to try to get the burble back, or leave well enough alone.
Due to the modular design, I can replace the original mid section, or the rear mufflers or both in combination with either of the new sections if I get really bored and want to play.
I am getting an extra mounting bracket fitted to the middle of the new pipe section, but after that, I will try removing the new rears to see how it sounds.