The way you are explaining the sound being tinny while on the bike but has a fuller sound when away from the seat make me wonder if you have the speakers out of phase which would cause a tinny sound in the seat.

It is a learning experience when tuning to be able to hear speakers out of phase.
You can check phase with a AA battery.
Unhook speakers from amp, pay attention to which wire came from the + and - on the terminals. Touch the wire that came off the + to the + side of the battery and the - on the -.
If wired properly the speaker will move outward. If the speaker moves in it is wired backwards (out of phase) Repeat process for the rest of the speaker.



Explore the headunit setting some more as it should have seperate xovers for front and rear.

You are better off using the seperate crossovers on the headunit than the amp. The place you had do the install should have set the xovers if they are any kind of a reputable shop.

 

+1 - listen to these guys...great unsolicited advice!

 

IMO this is a big red flag. That makes me think this manufacturer does not understand motorcycle audio. As others have mentioned we have to push these little speakers way too hard for them to be able to reproduce lower frequencies without distortion. Distortion will result in damaged speakers eventually.

Babyboy makes a good point about checking the phase of your speakers. One set of speaker wires reversed can mess up the sound of an entire system. Keep reporting back with your findings, they will get you straight.

 

The speaker wires coming out of the amp are not very accessible they're kind of blocked by some things I wouldn't be able to pull them all out and get enough slack to spread them across double a batteries. Is there any other way to test for that? For my whole life I always thought if I accidentally put the plus and minus speaker wires in backwards it felt like I noticed a terrible sound quality immediately and like a lack of bass. That was with like home stereo systems and stuff though. I could just like reverse the terminals on the speakers one at a time and see if I can tell any difference better or worse but I don't know if that will work.

I came across something else yesterday that I was reading that said a certain high frequencies as super high volume could possibly be sort of bouncing around a bit in the fairing if that makes sense. When I was saying that it sounded a little jumbled when I was super close it got me thinking, I've been to a lot of concerts and I get the same sort of effect if the volume is too high or if I'm too close to one of their speakers. The highs just start ringing in my head and sounding messed up. So it could just be me.

 

What ever is easier to check polarity but preferably off the amp. If you have to take the amp loose take it loose to double check the work OTHERS have done. People get distracted or in a hurry and do silly ****.

Make sure you set the crossovers either in the HU or on the amp you will thank yourself later.

 

Supposedly an app on the Apple Store can help you detect a reverse wired speaker.

Speaker Pop Wiring Tester

 

I bought one of these a long time ago, might have cheaper versions on amazon. Theres plenty of phase detection loops on youtube to use with this tool to check that all speakers are in phase. Doesnt matter if you get 3 positives and 1 negative pulse or vise versa when comparing to the testing loops, just important that all speakers are the same.

https://volunteeraudio.com/products/...lUZlij81ijUX6G