Base line setup that came on my SR8 - odd to say the least.

Richard, can’t you get a quiet exhaust from Radical?  Or do you already have the quiet version? Do you know where the sound booth is?  Is it in the same place every time?  Laguna Seca has very strict sound restrictions (many days are 92 dB... or less).  Nearly everyone puts a 90 degree elbow on the end of the exhaust to divert the sound away from the sound meter.  For Laguna the best angle is to the left and up a bit.  Also some people have had luck adding a Supertrap muffler on the end of the current exhaust.  They guys that race in the Radical cup figured out that a lot of the sound comes from the intake and they were able to reduce the sound by 2 dB bu putting fuel cell foam into the intake.

  Hopefully Dennis will chime in because he has a lot of experience passing sound at Laguna.

Charley

I've been wrestling with sound at LS for years. Had to give up on the Atom when they went from 92 to 90dB. Couldn't get it to pass with such short pipes.

Which actually was the catalyst getting me into the PR6, finally got my 1440 to pass with a Walker 18142 (summit or Ebay) 2.5" in/out. And can go flat out at 89.8 but under 9k rpm.

Previous variant was another Walker 17868 F150 muffler 2.5" in 2.0" out. This one will pass but decided to try the above to try a same in/out. These are cheap enough to experiment with, it's the track day that's the expensive part to get meatballed. Have some titanium straight through design, probably a motorbike can, that runs 96+ I run that one everywhere else.

Another reason I went with these is they are a single offset and do not have packing to blow out. I would regularly blow out the packing with variants I tried with the Atom. 

Did not have any luck with the radical overly expensive "quiet" can, where others have. Plus it's a larger diameter can that won't fit between my not original rear wing supports.

I don't seem to have trouble with inlet, my Rilltech airbox seems larger than factory box, but it seems to be the last 1k rev's makes the difference. I'm just running HPDE days so I have a 90dB lap time and a 92dB time, I just factor that into my expected outcome. My goal is to run every lap of every session so I'm willing to trade a little lap time for seat time.

I have the “quiet” mufflers already but I’ll venture saying they need repacking.

I also received a brand new set of standard small can mufflers from the guy I purchased the SR8 from on Friday - not enough time to get them installed.

I plan on integrating the small cans into the intermediate pipes (the two that pass through the rear suspension), just before the 90 degree elbows.

Sound check - AMP has two of them. One on the outside (left of) of the main straight and one on the outside (left also) of a shorter back straight.  I’d been short shifting and lifting a bit when I’d pass them.  I got a point by on the main straight and, well, that let the loudness genie out of the bottle.

After getting the pipes modded and mufflers repacked I should be below levels - but I also am going to look into a set of 90 degree elbows to point the sound towards the right side of the car, away from sound booths. I might make them slip on so I can point them as needed - example would be Laguna, where they’d need to point to the left.

I wonder just how much sound comes from the intake?  I know in my little off road stadium race cars the intake sound was intense to the point that good ear plugs were required.

The sound guy came by during lunch and asked if I’d lost part of the exhaust.  Said I’d been consistently in the 93-94db range at both stations then blew past at 101.  He mentioned putting 90s at the ends of the pipes, pointed slightly downward and to the right also.

The foam in the intake should help quite a bit.  One Motorsports did a lot of testing to find a way to get the cars quiet enough to run at Laguna and they got 2 db from the foam in the intake.  For the 90 degree elbow on my car I just clamped one on and could move it... but, some of the SR8's have a lip on the exhaust outlet so it may be a little more tricky.  Here are some picture of my simple SR3 set up.

Charley

Yup, that's what I'm thinking about doing - and you are correct, both of my pipes have a rolled lip on the ends - easy enough to fix, as I've been fabricating stuff like that (and full vehicles) for years.

Have done a couple of things since last weekend:

Put the car back on the scales and rechecked my weights and ride heights. All good.  I moved 11 pounds across the front with some very minor spring changes and, in the quest to gain a bit more rear end traction, put the stiffer anti-roll bar back in up front.

I also chased down an itty bitty coolant leak where one of the coolant tubes in the radiator meets the tank.  What I originally thought was a trans fluid leak (because of color and smell of the muck in the bottom of the side pod - there was oil spilled) was coolant.  Boy, I’m impressed with the amount of things riveted together in these little beasties.  I’m hoping I got the coolant system bled.  There are a couple of spots in the V8 system that allow for air trapment.

Also in the quest for a better driving experience I worked on ergonomics by pouring a seat insert.

It’s not covered yet and there are a couple of thin spots I need to attend to.

One bummer was that I lost my ponytail during the pouring process.  Let me tell ya, the foam sticks REALLY well to hair. ?

Looks like you are making great progress.  I am surprised that you poured the foam over your existing pad.  Most people take the pad out.  

Charley

I considered both ways but decided to keep the pad in for more elevation.  Without the pad my vision was back below the dash.  It fits into the pad really well.

The new seat insert has made a world of difference.  I'm comfortable, feel well held and am able to steer the wheel instead of hanging on to it.  I will probably end up pouring another, now that I understand the process and know more of what I want as a finished piece.

I'm really surprised at how temperature sensitive the tires are.  The first session this morning was just below 60 and the track was fairly cold and boy the car is skittish until you get things warmed up.  Brakes have no feeling (easy lock up) and it's a tad spooky until it's woken up and has worked some heat into the systems.

The stiffer front sway bar definitely gave the back end more confidence at the apex.  That feeling of it wanting to step out is dramatically less.  I actually found it would drift all four instead of trying to spin on me, which was a pleasant surprise.  I never set out to drift it but the three times it did, I felt quite in control of the situation.  It does seem to want to understeer going in on slower, tighter corners.  A little trail braking, to load the front end a tad, is where I would experience the drift.  

Pressures came back about 2.5 psi higher than the recommended 25 for the Michelins so that may have been some of the sliding issues.  Temps warmed up about 15 degrees from the first session out.

I'm learning more each time I take it out.

Richard, I also want to pour my seat with 2 component foam but I cannot find any source about "what material, where from".

Do you have any information for me that could help to find the right stuff?

Thank You

Alex 

Alex, I also run with a poured seat. It's really a "required" addition. I got my kit from OG Racing in Virginia:

https://www.ogracing.com/bsci-eis-w50-sfi-seat-insert-kit

BSCI is the manufacturer.

I made mine (twice, so I'm now an expert, lol), then sent it to my car interior guy. He covered the whole insert in 3mm memory foam and then covered that with the included flame-retardant outer cover. It cost me $150 for that bit of custom work, but the insert works very well. When driving, you completely forget about the G forces, and you are just looking for where to put the car, etc. 

John, please post a picture of the finished product. Getting it finished by an interior pro sounds like a great idea. 

Charley

Sure thing!

Wow, that looks great!

Thank you for posting,

Charley

Thank You John, with your help I have found a supplier in Germany for exactly that kit!

It comes in different sizes, starting from 27l foam and 450x700 mm cover. Is the smallest enough for the job?

Thanks

Alex

P.S. This forum and you guys are great!