Dual mandrel "X" OR single "Y" Better?

[spf_lexus]

Awesome, I plan to try using the stock Y with the rebuild. I indeed have my stock system but its at my parents house 1300 miles away so if shipping costs are not too high, i'll have it sent. As for the rush header "reaction" to the stock Y, I feel that the system will give much better throttle response because its going to be flowing more cfm at any given rpm, so the engine will still be within the stock Y's limits flow wise and a little closer to the vvt engine class overall. Once I get to thge point where I rebuild the engine for 11:1 or 12:1 cr, I may see a need to create a slightly larger nozzle but for now im sure it will work great.

Most mufflers slip OVER the pipe feeding them. Check the internal diameter (ID) of one of your Magnaflows

The magnaflows slip over my 2.25".

 

[spf_lexus]

I also like the idea that its almost a straight shot to the rear bumper. I noticed my current setup can get a bit raspy when free revving the engine (no load). WOT sounds good but overall the system lacks bass. During my LS400's early days I ran a $2000 JIC magic dual titanium canister catback w/ dual 80mm's mimicking the stock layout... and man it was LOUD. It was bornerline obscene but the lack of raspiness and the dB's of bass it put out sounded epic and to me I never felt that I needed to put the silencers in. Will this setup that consists of a "quad-y" layout where the headers merge 3 times and the header back merges another time lead to a more solid note with more "bass"? I'm planning to run mandrel pipes and a high quality canister style muffler w/ 2.50" slip on and 4".

 

[JBrady]

I also like the idea that its almost a straight shot to the rear bumper. I noticed my current setup can get a bit raspy when free revving the engine (no load). WOT sounds good but overall the system lacks bass. During my LS400's early days I ran a $2000 JIC magic dual titanium canister catback w/ dual 80mm's mimicking the stock layout... and man it was LOUD. It was bornerline obscene but the lack of raspiness and the dB's of bass it put out sounded epic and to me I never felt that I needed to put the silencers in. Will this setup that consists of a "quad-y" layout where the headers merge 3 times and the header back merges another time lead to a more solid note with more "bass"? I'm planning to run mandrel pipes and a high quality canister style muffler w/ 2.50" slip on and 4".

Sound is hard to predict.

Generally larger pipe makes lower frequency waves.

That said, just like a tuba or trumpet can make a large range of sounds depending on which keys are pressed an exhaust systems sound is based on all its variables including pipe length, diameters, merges, volume changes, curves, engine dynamics, catalysts, resonators, mufflers, location of outlet(s), shape of outlet(s), materials of system, state of tune and more.