The only time an 8" is an upgrade is when going with a full 3-way front stage. A lot of 6.5's struggle to play high enough to pair with a tweeter, that's why a good tweeter is so important in the traditional 2-way front stage. If you go 3-way active with the 8" you can certainly be more midbass, but honestly, a good 6.5 that is blended well with the sub(s), is plenty. I'd say that if you go with an 8" you are almost required to go 3-way, so in that case, I wouldn't say it's worth the hassle (unless you planned on going 3-way anyway). A 6.5" can do very well in both a 2-way or 3-way, when paired and tuned well, so I don't think you should feel any obligation to upgrade.

 

Maybe even a 6.5 ported under the seat?

Sent from my XT1710-02 using Tapatalk

 

In my old Mazdaspeed3 I went from a 6.5" two-way to a 6.5"/3" 3-way to an 8"/3" 3-way. In hindsight here's my experience:

- The 8's (Beyma 8BR40/n) played down to a 63hz high-pass effortlessly, while 2 different sets of 6.5's (H-Audio Ebony in the 2-way, Mach 5 MLI-65 in the 3 way) both sounded strained at 80hz and sounded best at 100hz. The 8's punched hard and were nice for filling-in a 65-75hz hole in the subwoofer's response, likely due to the car's acoustics.

- After experimenting out of curiosity, there's no way I would run 8's off-axis in a two-way unless you are running full-ranges or large-format tweets that can dig very low.

- Door-mounted woofers that can play low and loud create all kinds of resonance issues. The 'speed3 was particularly bad because the entire inner door skin was plastic, there was no metal at all to mount the woofers to. I could feel the entire plastic panel (not the interior panel but the one behind it) flexing like crazy with the 8's, which made for very "dirty" midbass in the 80-100hz range due to resonances. If you want your door-woofers to play low and loud, I'd say you need very strong mounting, bracing and dampening to keep the midbass clean. I actually had much cleaner midbass in that car crossing the woofers at 100hz.

 

This is very timely. My son has an '08 Speed3 and has been itching to dump the Bose and put something fun in it. I have an old pair of PHD 6.1 PRO that I was going to put in the doors and hunt for some good tweets to pair with them. We'd get rid of the Bose amp and use a minidsp to run full active off the stock head unit.
How much trimming did it take to fit the 8's in the doors? In my RX8, the plastic inner liner is a blessing and a curse. I pulled the doors off to do everything (you have to in order to get the speaker wire through the connectors invisibly), so it was really nice to be able to pull off the whole inner part as one piece. It made sealing and deadening 10x easier than on other cars since you can get to every surface. But the downside was exactly what you're saying. I used CLD and CCF on both inner and outer skins, then braced the plastic (as best I could...). Then butyl rope. Then CCF between the plastic and the door panel. It took some doing, but they are solid. Does the Mazdaspeed have the same set-up (being able to take the whole inner piece off easily)? I haven't had the doors apart yet.
Where did you put the midrange for a 3-way? That's been the biggest question for me. I prefer dedicated midbass and midrange when I can do it, so if it's not a terrible amount of work, I'd love to go that route.

 

It really depends on which 8. Could be a better move, could be lateral, or could even be worse. Gotta pick the right piece of equipment for the job

 

With those big HAT midranges, the larger midbass may be the correct choice depending on your tweets, what your lower extension is like on the mids, and other factors. How are the HATs installed?

 

AD w800 NEOs will play to 40hz and the SW/W800 (non neos) will play to 30hz with authority but you arent getting either for $400. Also if you are running a 3 way, why is your mid not playing until 700??? Can it not play lower?

 

Long story (which I typed out once, but the submit bombed out). But let's just say "no." I'm conservative with my high-pass, typically, and I felt better about not putting the juice to it until that point. Realistically, I could drop it to 500, but the difference wasn't noticeable enough to abuse the drivers. That's one of the reasons I want to move to the L4.
I have a 9" hole and very thoroughly deadened doors, so thought if I was ever going to play with big midbass, this would be a good car. It's just that I want the car to be easily returned to 100% stock, so mounting the 4" midrange will be tricky (right now midbass and midrange share the hole). If there's going to be a big gain in midbass performance, I'll do it. But if it's going to sound pretty much the same, it's not worth all the hassles and fab work.

 

That's what she said...